My grandma is wheelchair bound but when she's agitated, she will attempt to get up and lose her balance. Although most of the time, there was nothing serious, but a fall is still a fall.
Hmmm firstly, I would suggest switching up your grandma’s wheelchair (WC) to a WC that is slightly reclining back. This way, she would have a hard time trying to stand up.
Secondly, I would suggest a WC alarm which consists of a chair sensor or a chair pad. The sensor in the alarm will detect reduction in pressure on the chair and set the alert off, alerting anybody nearby who will be able to help your grandma sit back into the WC.
Hope this helps!