Hi Kim,
I know it must be heartbreaking and frustrating to see your mom this way . The problem is that most likely you can't reason with her. Whether her problem stems from the brain mets ,medication ,or both, the fact is your mom just isn't herself and she can't be reasoned with. Somehow, you need to have the doctor tell her she can't drive for now. Perhaps if she believes she can drive at some future time, she will be okay with it. BTW, I sent you that file on steroid psychosis. Hope you received it. Good Luck and God Bless you.
Love,
Sue