How do I get my Mom to move out when she gets part SSI?

You could ask about family mediation. Some family service non-profits have mediators who help people through these situations.

Were was she living before she moved in? Maybe your mom can get subsidized housing, however there is usually a waiting list. Ask the family services people what is available in your community. They an probably help you find a way out.
Good luck,
Carol

usually people say "my house, my rules" and like you told her to move out. maybe help her find a place that she can afford. and most people do not want to touch what they have saved, I know my mother doesn't but I tell her she has plenty and not to worry, but if they grew up in the recession that is a big deal to them. maybe you could ask her for suggestion in what she is finding fault with, tell her you tried that and it didn't work. then try to find her a place before you both begin to hate each other.

I would just move out. That away, it will push her to find her own place. I am going through something similar with my mother, and now we live in a 3 bedroom. I told her that me and my daughter are moving out into a 2 bedroom. Now she says she is going to have to move back to Chicago or get a low income apartment. This reinforces my mother that she can longer stay with me.

If she gets SSI, which stands for Supplemental Security Income, she can have no more than $2000 in the bank, and your providing room (and board?) in your own home can be expected to reduce the size of her check, because it is "in-kind" income. Did she report the change of residence to social security? If she is getting ordinary Social Security retirement, rather than disability, then get her on every waiting list for housing your can think of. A centralized Section 8 wait list, local waiting lists for low-income / elderly housing, and the sooner the better. If you take Tatianna's suggestion, it may help move her up the priority list: on a date certain, she's going to be homeless because you won't have room / can't afford to support her.

It's tough to be in the middle of the "sandwich," taking care of a disabled child and dealing with an elderly parent. I feel for you. She raised you so that makes her an expert, right? :) But only you know what's best for your daughter.

How much is a good amount? You know, that could go quite fast even when she receives her part SSI.Still not your problem if she's nasty to you.

Carol's answer is the best. The initial friction can stem from different ways different generations think things should be done and especially if you are getting medical advice which is not what would have been given in Mom's day and following it, maybe things could be ironed out and it does not really have to be "my way or the highway" time on either side. Can you share any specifics about the conflict areas?

Yes, u say partial SSI retirement. You get SSI when there is no other income. Social Security you can start collecting at 62 (60 if a widow). She may be getting help from Medicaid with her income.
Sorry its not working. But would be better for all if she moved out. If low income she can get help with housing especially if on SSI. Foodstamps and help with utilities.

Not income, health insurance.