How to Convince an Aging Parent That They Need Help?

if she has a doctor she trusts, see if y'all can schedule an appt. talk to doctor/nurse prior to appt to tell concerns. he'll talk to her about it in the appt & mention the type of care she needs.
i worked for adult protective services for 4 years and dealt w/this situation SO much. it's SO hard on the families, i can't imagine if it were me. i'm dealing w/a VERY similar situation right now and told the son if he didn't get more care in the home i'd have to call APS (i don't work for them anymore but still work for the elderly). you can't REALLY convince her. she's not safe to live alone, period. she can have that aide come in or she can move somewhere for more supervision. it's kinda how we deal w/our toddler aged children. it's either this or that. say all of this lovingly of course, but she's not safe. that whole issue of the power being out, and dumping water down the toilet, if APS had come out at THAT time, she would've been removed from her home & placed into a safe environment if the doctor determined she didn't have capacity to make decisions for herself. i'm just being real w/you on how serious that situation you mentioned is. she has choices. either stay at home w/a "friend" (aide) or a more supervised facility, away from her beloved (assumingly) home.
take care keys. disconnect battery, etc. i've seen family do those types of things to keep them from driving.
oh man, i wish you the best of luck. like someone else said, get doctor involved asap. she's gonna be pissed at whoever wants this help for her so just try to remove your feelings from it as hard as that is. she's probably got alz/dementia, so just remember she's not completely cognitive & she's also really upset she's losing her independence, rightfully so. i rambled a lot, sorry, but it brought back the days when i did this for a living and obviously i still have a soft spot for it, even if it doesn't come across that way. good luck... :)

It worked for my father to have the doctor tell him he could no longer drive. That way it was not my mom's "fault". He still did not like it and did not believe it, but mentioning that he almost killed a bicyclist since he did not see him helped. Can you speak to her doctor in advance and ask for his help in advising her that in his medical opinion she should no longer drive, not because of a danger to herself, but a danger to others?

How about an assisted living type of residence. Of course I do not know
your financial situation. Tough situation. Definitely take her car keys
from her. If she ends up in the hospital in the near future, make sure you
meet with social services to help you with some sort of discharge plan.
Good luck.

Oh, S., I know how it is.

My dad will be 86 on Friday, but he has been exactly like your MIL for the last few years. The difference is my sister, BIL, nephew and myself live with him, and we have been there to pick him up when he fell, call 9-1-1 when he has emergencies, do his banking (he still mishandles cash, sends it in as payments) take him to the doctor, do his shopping etc.
He is dying from kidney failure, cannot walk further than to the car, has diagnosed dementia, and STILL tries to call the shots! Until his recent development of Sudden Onset Dementia he criticized EVERYONE and EVERYTHING, now it's here and there.

But, 6 years ago when he almost died he gave my sister Power of Attorney in the event he could not make life or death decisions, and handle his money, and now that he has dementia he cannot revoke it.

You need to put the the bills in someone else's name who can pay them, insist that she keep the aide, or move her into a nursing home or into one of your homes. She also needs to relinquish her driver's license, which my uncle of 84 just did last week. But unless you get her to sign a Power of Attorney over to one of her children now, she legally will not be able to do it if she is diagnosed with Alzheimer's or dementia, or has a stroke or heart attack and is unable to understand what she is signing. Then the state she lives in will make the decisions for her care and her money, not your family.

Contact an attorney to discuss drawing up a Power of Attorney,
God bless ♥

Maybe you can sit her down and show her the math (it will be a lot cheaper to not do the upkeep on a car and the gas and insurance etc) and that she will then have that money to use on a cab once in a while when she needs to go anywhere. I am going to be running into this soon with my mom.

Do you know the name of her doctor? Id start w a call to him- he may be offer some insight and prob give you some resources to consider.

The other trick i havefound w dealing w my aging parents is to have your idea presented by someone else - non famiily. Like her dr or trusted friend. For some reason its like we are kids again and they ignore our advice, but if they hear it from someone else they are like.....why thats a great idea! Worked like a charm w my mom. Shes stubborn too.

I am not sure where you live, but there are some amazing continuing care retirement communities that are great for people who still feel like they want their independence. The idea is that they can move into independent living while they are healthy so that "should the need arise" (even though it already has...) they will have access to any kind of care they need (often at a discounted rate - check with the community on that).
I worked for one of these communities in a neighborhood where the same depression era seniors were always against leaving their homes. Their children often had to come together and insist that the parent at least VISIT the community - often times these seniors think of them as a "nursing home" and visit to find out that they are like living in a resort. That might help? Tell her you don't expect her to do anything - just go SEE. These places always host non-threatening events like luncheons, so call the places closest to you, go visit without your MIL and pick one or two that you think would work with her financial situation and interests - then get on the mailing life and her HER on the mailing list. THEN, go to a luncheon with her?
Anyway, best of luck to you - remember that this generation has gone through a lot and they are TOUGH! :)
Do me one favor, though, don't take the advice of anyone who says to treat seniors like children. They are NOT children. They have lead long lives and have lived through a lot - give them a little credit!!