It is terrifying for everyone. I know it's terrifying for our moms to feel it and I also know it's terrifying to watch.
So many people are caught in the bind of having work and kids in school far away from parents, it makes it very hard. We were even close by, by choice and by luck because we all liked the area where we grew up and there are work opportunities here, but honestly it got to the point where even someone being with her at all times wasn't enough.
There are still good memory care facilities around if you look at them carefully. Don't look for the fancy new buildings--look for a real community with as low a staff turnover as you can find. I wish you and your mom luck.