I think all Grandmothers need to set boundries for themselves.
For years we have been at the beck and call of our children because they are are responsiblities. Then they leave the nest and want to be on their own, then when they have babies they want us to still repond to their needs. I would just announce to the family that you are now getting on with your life. Now out the freedom years and your responsiblitys are those of yourself and your husband. And the choose to be with Grandchildren is yours. You can say "No." I know it is hard but look in the mirror and try it once/
Your daughter is being selfish by wanting you in her home (it lessens the work she has to do by coming home to a baby already tucked in and sleeping. What a good deal). However, she will not see it that way - so you will have to point it out. After all she has been your child and has been catered to all these years. She will not understand that your needs have changed.
However, you are right to want to do things that help but in a way that you can also be comfortable doing it and not resentful, which will eventually cause a riff between you and your daughter. Simply put: being in your daughters home inhibits you from being in your own nest doing what you need to do there. It will also deprive your Grandchild of feeling safe and carefored by his/her Grandmother is a space that is hers.
Talk to your daughter - then make a schedule of your own. Decide how often you are willing to go to her home. Once a month - once every 6 months however you what it. Then you decide how often you will sit in your own home. Then insist that if they respect you they will understand. This is their baby not yours. If they want someone to come to the house then they will just have to hire someone and pay them.
That's what I think anyway having already battled myself through Grandparent years. P.