I used to be the Director of HR at one of the agencies in BCS and while I do not work in that field anymore, still have a great relationship with the owner and the staff there. I can let you know a personal contact at this company if requested and happy to connect you. They're the leaders in Alzheimer's care and training for their field. My email is whoop03 atgeemaildotcom.
In my role there you would not BELIEVE what I saw from people who applied to be one, were denied and worked privately for folks, etc. I encourage you to do whatever you can to use an agency. Research if she/he may have a long term care policy that may cover in-home care, sell some furniture, etc. but please use a place that is state licensed and bg checks, screens and does site visits weekly, has an obligation to have someone there regardless of illness, and MOST importantly trains their CG to deal with those who suffer from Alzheimer's specifically. That is why they're expensive.. it costs money to do it the right way. Not only will that make a difference in the sense of peace you have when he's gone, but, they'll well be equipped to deal with the many facets of what that disease can present.