WOW! How sad! Can you get in touch with their kids? Maybe they can go over and check on her/them. Just keep an eye on the cars and window coverings. See if there is any movement. If you see absolutely nothing, call the police again and let them know you are concerned. They obviously have records indicating they have been out to that house before and have even taken the husband into custody, even if he was not booked.
If you do see the wife, and you feel comfortable, talk to her privately. Let her know you and the other neighbors are not being nosey but concerned. Let her know there is help for her.
I hope it all turns out OK.