Mom is restless at night (and incontinent), removes her pants and brief in bed. Any suggestions of pants that she could not easily remove?

You dress her in an Alzheimer's anti-strip jumpsuit with a Depends with a liner for extra absorbency:

https://www.amazon.com/Talit-Inc-Womens-Alzheimers-Clothing/dp/B07KMD5SMH/ref=sr_1_1?crid=3MFTIGM92VYVJ&dchild=1&keywords=alzheimers+anti+strip+jumpsuit&qid=1615673916&sprefix=alzheimers+anti+strip%2Caps%2C370&sr=8-1

Good luck!

You might go with a diaper at night instead of a brief. I remember having kids who'd take off their diaper, and the trick to fix that was to put it on backward. They couldn't figure out how to pull the sticky tabs to undo them.

It's called "adaptive" clothing and they're designed so that the wearer cannot easily take it off.

https://www.silverts.com/shop-by-need/adaptive

Possibly one of those 'snuggy' type pj's with the feet in them. I think they zip down the front. We used to put them on the kids when they were babies. I'd be careful about the slippery feet--maybe put some iron on stuff on the bottom of the feet--fabric stores sell this.

They make a lot of these, I see whole families posing for Christmas card pics in matching ones. Even if they don't have feet in them--if the zipper has a 'cover' on it, that may be enough to foil mom's escape.

Does she take something to help her sleep? A mild sedative could help keep her asleep and the restlessness could settle down.

This is a common problem--I hope other have better suggestions.