I was very surprised when you mentioned the credit card at that point in your story, wouldn't have expected her to have one in the first place, given her circumstances and the spending patterns you describe. But then, that's probably a question of differences in banking habits between countries (nobody in here ever uses checks for anything, and credit cards almost exclusively for online purchases and traveling abroad - everything else is by debit card, and hence also no issues with outdated account balance information).
Maybe between generations? I almost never use checks except when paying a government agency (car tags, property tax, school stuff like sports team fees) Mother in Law is in her 80s and is not prepared to adapt.
The bank has already cancelled her checking account and credit card account. (Cancel may not be the right word for the CC - she still owes the debt but may not make additional purchases). I think the bank is out of the loop at this point. It's between us and the debt collector now.
My wife spoke to our attorney (who is not a bankruptcy guy) a little when she was setting up our appointment to get a Power of Attorney. Mother-in-Law doesn't really have assets to go after that are available to creditors in bankruptcy, so adding more charges is going to drive us to that option.
She gets lost, but she doesn't really drive in an unsafe manner, and she doesn't go outside of her (shrinking) zone of familiarity. She even changed churches so she could avoid driving across town. The connection between the two is a legal one - if we actually take control of her life with a guardianship then we are liable for any damages she causes while driving, so whether or not she drives would be up to us at that point. I mean, if we become her guardians that of course it's up to us, but ALSO the increased liability seems designed to make us err on the side of taking away her car.