My father is 82 and half the time doesn't know who I am. When I lived with my parents earlier this year, it was not unusual for him to ask me if I had seen Michele as he had mail for her or the phone was for her. Because my oldest son has executive function difficulties and I know a reasonable amount about the different kinds of memory we all have, I was never disturbed by such things. I realized that in some way he knew and trusted ME, he just couldn't match up my face with my name and seemed to think I and this Michele person were two different people. (Certain supplements helped him some and I think more could be done if my mother believed some of the things I said. <shrug>)
Not that it is any of my business and not that you asked, but I highly recommend she get a book called "How to avoid a hysterectomy" to help her with this important decision.