My best friend's mother had Alzheimer's and lived out the last five years of her life at Belmont in Burbank.
Her family (my buddy and his older brother and younger sister) spent a bunch of time researching/interviewing local facilities and felt this was the best in the local radius.
Not cheap but was able to handle everything including, sadly, end of life care.
Good Luck and as someone who lost his mother recently (me), I understand your pain.