Hi, Sue,
I know how difficult this time will be for your family. I am sure that your parents will initially not be happy since they previously refused to go. However, I think that once they get there, meet people, build relationships and develop routines, they'll adapt. You didn't mention how your dad's health is. Is he physically and mentally healthy? If so, then you may want to focus on winning his approval as early as possible after the move since what he says may influence your mom.
As far helping your mom through this transition, know that there probably will be some initial decline in her mental state after the move, but know that she can come out of it. We moved Mom three times (into the nursing home once and then two more times to two different wings). The tricks I learned included the following: (1) try to place some items that she is attached in in their room(s) so that she will feel at home prior to moving her; (2) be present the day of the move; and (3) be present as much as possible for the next few days after the move.
Also, be prepared for unusual outbursts. In our case, shortly after Mom made the last move, she started yelling at my brother and told him she wanted out of the nursing home NOW! And when he didn't reply immediately, she told him he was no longer her son and to leave. That response from Mom shook my brother up, although later that day when he went to visit, she didn't remember the conversation. I had seen some similar outbursts when Mom moved before, so I was able to counsel my brother (who was in town to help with the move since I was out of town).
I wrote about these moves in several blogs, which you can find at:
http://www.healthcentral.com/alzheimers/c/42/1830/make-smooth
http://www.healthcentral.com/alzheimers/c/42/1851/adjusting-home
http://www.healthcentral.com/alzheimers/c/42/2332/day-smooth-loved/2
http://www.healthcentral.com/alzheimers/c/42/2502/caregiver-coach
http://www.healthcentral.com/alzheimers/c/42/7736/move-mom-newer/2
There's also another sharepost from the AFA staff that you may find helpful:
http://www.healthcentral.com/alzheimers/c/2016/24930/comments
Take care and keep us posted!
Dorian