I work in a nursing home and deal with dementia daily. It doesn't do any good to tell the person with dementia that they are wrong or that a spouse is dead> This just gets them upset and more agitated. Its best to go along with whatever delusion they are having. In your case I would tell your mother that he is not well enough to go home from the hospital and that he called and wants her to stay home> This may help and it may not. My patients are constantly looking for people who aren't there and wanting to get home> Telling them that they are home does no good so we usually tell them that there is a bad storm and we can't go out in it. Or telling them we are waiting for the bus or other ride. Then we try to distract them with another activity.This usually appeases them. If they are in danger of hurting themselves or someone else we usually give them Ativan or Haldol or Seroquel. Being a caregiver for someone with dementia is very stressful and you need to make sure you are taking care of yourself. There is no shame in having a hard time handling the situation.