First of all, We also had a grandfather who was in and out of Hospice for over 9 years.. amazing.. so in some situations they can get better, but NEVER count on it.
He needs to do what he needs to do. If in his heart he needs to go and see her.
Is she alert at all? If so, he should cal the Hospice and ask them the best time for him to visit. I will warn you, sometimes, they will ask you NOT to speak or touch the patient.. It depends on what they are dying of. So he needs to be prepared for all of this.
Then he needs to promise himself to not get pulled into the drama. He needs to go and either be prepared for them to be there in the room, or to ask te nurses to clear the room, so he can have some privacy.
Then he needs to be as gracious as possible. Be better than all of the others. say hello, not ask how they are.. and then just hold his tongue and get out as soon as he feels he has had enough time.
I have family members that thrive on drama. They are so ridiculous, I think they must live in their own minds and do not recognize reality at this point. I am polite to them. I say hello, I am polite but I also try to not get drawn into their games and their words.. It can be done.
I am sorry all of you are going through this. I wish there was a way to help these people, but I have just learned to stay away and not get drawn in.. It just makes it worse.