I agree with contacting an attorney. Your aunt sounds nuts. I read both of these posts and agree that there should be no personal contact between the two of them. If your mom is in a care situation/residence, caregivers should be notified that aunt may try to contact directly, just for your mom's own peace and safety. You don't need to give the caregivers a lot of the drama, just "This person has attempted to get money from my mother on several occasions and we need to make sure Mom isn't manipulated."
So sorry you are going through this.
Not go be rude, Rhonda, but some people you just do NOT go into mediation with. Some people are so emotionally dangerous and manipulative, it's foolish to even be in the same room with them. It would be great if things could be worked out-- mediation is when ALL parties seem to be reasonable and want to work toward an amicable solution. The out and out lies described previously already suggest that it would only be folly.