Hey, shortstuff. I'm short, too. Lots of good questions: a decision point for sure. So much depends on where she lives now and where you and her other children live: some benefits for disabled elders are federal and some are state. She's now in a very affordable apartment: can you talk to the nearest area agency on aging to see what additional supports she can get there? Maybe she's eligible for free home care for a few hours a week. (We have a program here in Oregon like that). You can find out about that and other supports at https://eldercare.acl.gov/Public/Index.aspx.
She probably is eligible for Medicaid if she's in HUD housing. But if you're going to change states, then it doesn't make sense to apply in one state only to move. Ask the area agency on aging that you located on the Eldercare web site about eligibility, and you can also talk to the agency that serves the zip codes you're thinking of moving her to. If the state she'll be in does have assisted living that's paid for by medicaid, then you're in good shape.
You might get additional suggestions on the facebook aarp caregiving site: https://www.facebook.com/groups/1353173708169053.
Can you have a 'family meeting' on zoom or facebook chat to talk with your siblings? This should ideally be a group effort.
Good luck,
Jane