Having difficulty in moving my parents into Independent/assisted living. Any advice on what other ways to make this happen?

My parents are 83 and 85 years old. My dad was diagnosed is Mild Cognitive Impairment last summer. Alzheimers runs in his family so, we had him tested and he is currently being treated at age 85. My mom is not that independent and relies on my 85 year old dad to run their daily errands etc. Mom cannot keep up with the daily run of the house anymore and is becoming more and more frustrated with day to day chores and my dad. I have been trying to discuss this move for the last 3 years. I found a place closer to me, as they live 100 miles round trip away from me and my dad has been hospitalized twice already this year. Until this last year, they have done pretty well on their own, but now I can see life becoming more and more of a struggle. I found them a two bedroom apartment in an Independent/assisted living 5 mins from me. Their house is 61 years old and has not been properly maintained in the last 15 years since my dad has had health issues on and off. My two siblings live too far away to help. At Christmas I took my parents and brother to the place I found and my Dad declared he was ready to move. Actually, my Dad has been ready for a couple years now. He wants to quit driving and having the responsibilities. We put the money down to secure the apartment and they did come and fill out the lease paperwork and paid the community fees and have scheduled the first rent. My hope is to have them moved this month...but as this is becoming more of a reality, my Mom is becoming more and more agitated. She is angry at my Dad for having to move, she is angry at us kids and is making herself sick. I have done all of the things recommended to ease my parents into this situation....slowly discussing, looking at places, they have friends and family members that have positive experience with this, I have pointed out the need when the situation was right, I had my Mom agree this is necessary, I have moved things already out of the house at their request, they voluntarily had their paperwork done by the doctor to move, my siblings have pointed out the need to go, we have spread sheeted their finances to show they can more than afford it, Dads doctor stated is time to move, but yet I am having struggles with getting Mom to move. I have been sensitive to them leaving their home, but remain stern they need to go. They have to go before they have more issues and choices get narrowed.

I am concerned about my Dad walking up and down their steep driveway. He is not physically capable of keeping up with maintain/repairing the home anymore. I am concerned about my parents safety.

I am frustrated with my Mom, anyone else have this issue that has some good advice on what other ways to make this happen?