This leaves the OP in the miserable position of being blamed for their mother's "misfortune!" How can they handle THAT, even if they take this action? I think that's the greater question in a way! 

What happens when she blows through her household spending account? Does she understand there's only so much in there? She may not remember, I'm sure that's the issue. Ugh, the only suggestions I have are so unpleasant -- just to close her credit car...