My mom (89) has dementia. She fell a few nights ago and can't stand. She yells whenever someone touches something. What should I do?

ER. If you cannot get her to the car call 911.

ER.
There is a good possibility that something has broken. A hip, leg,arm or wherever the pain is.
Whenever there is a fall call 911 to safely lift the person from the floor. Do not try to do this yourself as you can cause yourself to get hurt or the person can be injured more.
At this point call 911 and they will transpire her. Taken by ambulance she will be seen faster than if you bring her in.

she may have broken something. You need to take her to the ER and if need be call an ambulance