How do we make the move easier on my mother with dementia?

My Mom suffers from dementia and is 90 years old. She cannot remember anything she does or his told after the conversation is over. My Dad who has been her caregiver can no longer maintain their home and has made the decision to move to a senior apt. where meals and cleaning is provided. Mom had been there numerous times over the past decade but doesn't remember the place. She has visted recently and says the place is nice but she isn't going.She gets quite angry when she finds out my Dad has made this decision even though she was part of the process. (I know she can't remember) The move is this week-end. How do we deal with the fact she doesn't want to go and will be very angry with my Dad again, about it. She will be mad if we let her stay y and be part of the move and mad if we take her somewhere and bring her there. All this very stressful for my Dad who doesn't need extra stress now. How do we help make this move easier. As of now he has her agreeing to clean the house of unnecessary junk. Movers will move their big stuff in the day of move. And we'll sweat the small stuff later.