Elderly mother in law being very stubborn...?

My mother in law's health and memory have been declining in recent years. My husband and his sister have been helping her with household and personal matters such as groceries, pay bills... but things have gotten worse, she would forget to hang up the phone (or pushes the wrong button), misplace her TV remote, eye glasses, panicked over running out of cough drops ...little things like that that she cannot resolve herself and my husband or his sister will have to drop everything and drive 45 min ~ 90 min (one way) to help her. She fiercely rejected the idea of having a nurse come over everyday to check up on her, although my husband and his sister visit her every weekend and help her with stuffs, but we all have our own life to take care of and sometimes it is difficult to be always at stand by. Needless to say, she also rejected to move closer to her daughter so it's easier to care for her. I always said that she needs to help her children help her, be cooperative, but she is making things more difficult, and I just don't know what to do.