How to care for an elderly parent in a nursing facility?

You'd have to get custody through the courts but you don't need custody to know what is going on with your mother in a nursing home. Do you have Power Of Attorney? It doesn't sound like it but I thought I'd ask. Even without POA, you should be able to visit your mom regularly.

Being friendly with the staff will generally help you feel more at home when you visit. Let them know that you love your mother and want to visit often. If they won't let you see her for some reason, then you contact the ombudsman for that home by going to www.ltcombudsman.org. Type the Zip code of the nursing home in the box and click enter. Then you'll get the representative's contact number. This person is there to help people with loved ones in long-term care.
Good luck,
Carol

Caution: becoming a guardian is very expensive.

I want to have custody of my mother while in a nursing home

Then you will need an atty, find 2 doctors who will agree and testify that your mother is incompetent to handle her affairs in a business like manner and go to court.