Mom's decision making skills are questionable. What do I do now?

Thank you for your advice regarding an earlier question. We're making headway with mom, 87, who still lives on her own in her home and still drives. She agreed to be evaluated for dementia next week. Some troubling signs include overspending, hallucinations, losing things and forgetting things left on stove (2 kitchen fire calls in May). Good news, she added me to her checking and we saw her attorney who is drawing up POA and her living will.
But, unbeknownst to me, she put her house up for sale and signed a six month contract. I found out as I had previously placed an alert on this house to notify me if it ever came on the market (it was previously on the market Feb 2018 for 21 days). Her only explanation is she wants to pay off her bills. Her checking is low, she still owes a lot on her home as she refinanced in 2016 incorporating an equity loan. She wants to move to a place where she's never lived, cost of living is twice where she is now, congested traffic, and little public transportation. I'm at a loss as to what to do now.