MIL holds onto furniture when you try to move her from chair/bed to wheelchair, suggestions to stop this?

Can you give her something else to hang onto? Is she grasping for something solid that won't let her fall because she doesn't think a human has the ability to stop her from falling?

Have you tried a walker? Mother constantly reached for something too far away and I've found the walker works just fine....so far.

She won't stand up with a walker, absolutely refuses. I know that the root cause is fear but this fear is causing bodily harm to others. She has totally given up with life and only feeding her keeps her alive. It is so sad and upsetting to watch this.

I might not understand exactly, but I think it's best to let her do that, I've always encouraged the elderly folks I've cared for to do that - go with their abilities, not argue against them - find another piece of furniture to line up next, or a handle on the wall - so she can move along a direction by holding onto the firm things. When you hold onto people, you end up totally dependent on different directions all the time, so you end up much more dependent and lose the ability to look and plan steps - which I find keeps the mind more agile! It can be very slow to take time to help them use their own energy, but learning to slow down to their speed is a skill I've found can help me understand them better.