Lexapro in low doses helps some.
I’ve been meaning to Google whether essential oils might help in dementia management. Lavender comes to mind as a good relaxant. It would be interesting to just rub some mixed into a carrier oil onto her back, where she can’t get it on her hands and then in her eyes. Or diffuse a bit in her room just to see if it has any affect one way or the other. You could have her sniff it first to see if she even likes it. Look for a pure one, I react badly unless the oils are truly therapeutic grade: Aura Casia and EO are easy to find if you have a health food store. No need for multimarketing channels like DoTerra or Young Living.
You could also buy some oils and have her sniff them all from the bottle and watch her reactions. If depression underlies her anxiety it’s possible something more citrusy would help.