Music can often make a huge difference.
I remember when mum was in her care home, the carers would put on old "singalong" music and suddenly everyone was recharged. Mum and others would sing along word perfect (even the lady who was normally mute), some would be tapping their feet, occasionally one or two would get up and dance and even the man in severe stages would be waving his hand in time. Sometimes the carers would get out percussion instruments for te residents as well.
If your mum responds to music, that is the way to go!
I just wish OH would respond to music, but he is one of the few that do not. He gets stimulus overload and cannot cope with sound