Doctor has done testing for dementia and mom is fine. What can we expect?

I'd get legal advice from an attorney in your jurisdiction. Different states have different standards for how they apply matters like that. Some people who don't have dementia are appointed guardians. I'd be curious as to why siblings want mom protected.

The thing about having a Guardian appointed for the finances, is that then it becomes under scrutiny by the court. Whoever is appointed then has to file annual Accountings, with attachments of checks, receipts, invoices, etc., that show where all the money is going and why. It's not like you can improperly apply the funds, since you have to show how it was spent only for the Ward. It's kind of a pain in the behind, but, provides good oversight. If the siblings are way off base, maybe the court won't appoint one. I'd likely get an attorney. The court appoints one for mom and she can tell her appointed attorney what she wants to see happen.  A lot of people consider having a family member living with mom or dad a great benefit.  They should be thankful to you. 

This would frighten me for mom. She should get an attorney to protect herself from her other kids and fix her will so they don't have to worry about her money anymore.

They think I am spending her money. Im not but mom said it's none of their business how she spends her money. They haven't been a part of her life for many years. They don't even check in on her to see how she is. They only care about her money. I do everything for her, happily so. I live with her and they don't like that I don't pay rent.