Is your Mom on Social Security? Does she have the funds to maybe go into an assisted living facility? Who is in charge of her financially and otherwise?
Sorry for all the questions but we went through the same with my Dad. He wasn't challenged mentally but physically and he made me Power of Attorney for both financial and heal care decisions. Of course, I did what he asked but it was still hard having to be "the one" to make all the decisions.
I feel the frustration in your post and hope you have some kind of help with making these decisions. Sometimes it's hard to convince our elderly parents that we're trying to do what's best for them. You can also check with the local hospital and see what resources they have for elderly care with regards to dementia specifically. I never realized how much help is offered until I seriously looked into it.
I'm praying for you.