M.T.
Sounds like he may be sufferening from dementia. The assisted living facility may have a social worker or someone who assists the familes of the patients who may have some more practical advice for coping. Does the boyfriend have any family? Does your mother have legal power of attorney? If not, speak to the social worker or the legal department at assisted living. A verbal request is not enough for someone, especially a non family member, to make financial decisions and manage the bank accounts for someone else. I know your mom means well but I'd hate for there to be any sort of legal trouble. Find out what services there are at the assisted living facility to support the families through this difficult transition. The doctor is there to oversee the patient's medical care, but not to give support to the family so find out who else there can help with this.
Good luck!