Unfortunately my mother-in-law was also the recipient of a lifetime of bad financial training. Actually, no financial training. She grew up on a kibbutz - the ind with the children's room and the socialist ideals. The kind that, per my understanding, was proven not to work because eventually they had to find a way to actually make a living.
She married very young, and from that point forward she fell into very stereotypical roles. She did all the cooking, serving, cleaning, sewing, etc. She never learned to drive. She once worked as a cook in a restaurant in Israel, and otherwise has never held a job. In the meantime, my father-in-law was responsible for anything financial. She really has no idea how much anything costs (other than groceries), how to budget, how to make purchasing decisions, etc.
I'm very concerned about how things are going to proceed. She is going to be living on a fixed social security income. My husband has already had to argue with her about a number of items that she has considered necessities that she just isn't going to be able to afford. (Daily newspaper, using a bank card when buying groceries instead of a budgeted amount of cash.) She unfortunately has to sell off a lot of their belongings, including items she really wants to keep.
I haven't had the warmest relationship with my mother-in-law, but love her and am very worried about how this is going to work going forward. I trust my husband to use good judgement, but still feel concerned about problems coming up from us being too involved with her finances and care.