What can I do about my moms sun downing? She is extremely frightened when the sun goes down and says she wants to go home and can't sleep.

Psychiatric meds. For my mom, she needed an increase in her antianxiety meds.

I'm not so sure that my LO had sun downing with her dementia, but, she did suffer with extreme anxiety throughout the day. She has Vascular dementia. She worried over small things and nothing. She also obsessed with things a lot. Her doctor prescribed a daily medication for her and it made a huge difference. She became quite content and the crying and worrying stopped. Later, when she had trouble sleeping she was prescribed a small dose of meds for that as well. Mental anguish can be quite painful, so, I'd discuss with her doctor for help. My LO takes Cymbalta, but, there are many options. I'd ask her doctor about it. Does he treat people with dementia often or does she have access to a geriatric psychiatrist?

Try to plan ahead and anticipate the sundowning. For instance, have a snack ready. Something you know your mom will enjoy. Some cheese and crackers or a cup of decaf (always decaf) or a piece of chocolate. Something small so her appetite won't be spoiled for dinner. Don't wait for your mom to become frightened, serve it a little before hand.

Make sure she's been toileted or is clean and dry.

Try to come up with some small distractions like a movie on TCM. I cared for my grandma who had Alzheimer's and I learned that she could only enjoy movies if there was a lot of movement on the television screen so I'd turn on a musical if I could find one (back in the days before we had DVR's). She enjoyed the dancing and singing.

Going into a sundowning episode just do what you can to ensure your mom is as mentally and physically comfortable as possible although it still may not be enough. And I agree with what the others said about medication. With the right medication your mom may not have to suffer as much.