How can I keep depends diapers on my mom?

It sounds as if your only option is to go with her to the bathroom.
She may hate the idea of wearing the pads, or else she could have memory issues.
If her memory is okay, try letting her know that she has more independence if she wears protection, because she is more pleasant to be around. Try not to show blame or anger. Just be light and let her know that incontinence can happen to anyone.
If she has memory issues, then she isn't "forgetting" on purpose. She may not be connecting with why the pad is laying there for her. She sees it, but the reason doesn't register. This,she can't help, no matter how much you reason with her. Accompanying her is likely the only way to keep her wearing them.
This is tough. I'm sorry you are going through it. Maybe someone on the forum will have more tips.
Carol

I do keep an eye on her when she goes to the bathroom. This happens at night and I'm asleep and don't know until I find wet bed clothing. I have discussed with her how this only happens when she sleeps (so she doesn't feel bad - and she doesn't) she is very tender hearted so I tread lightly and NEVER get mad at her.
I just keep reinforcing when she forgets. She thinks she remembers to put them on. It is probably she is half asleep??? I guess buy stock in Tide.

You could try putting a baby monitor near the toilet so you could hear when she goes and intercept. But you get -0- sleep this way.

OR - this worked for a long time with my Mom - I told her THE DOCTOR SAID she was not to get up and go to the bathroom at night anymore, as her risk of faling and breaking her hip was too high. (Mom was more likely to pay attention to my instructions if I told her the doctor said for her to do something)

So we took a last bathroom trip before bedtime, and then the bathroom door was CLOSED and LOCKED until morning. I even put a chair in front of it! This cut down on my washing tremendously - and also kept me from the worry that Mom would fall in the middle of the night and i wouldn't find her til morning.

are you using the pull up depends. My mom was always feeling like she was going to have an accident before she had her surgery. She would wear depnds but never actually needed them.She liked the pull up depends because they are very much like underware and very comfortable.