How can I get her to stay in Assisted Living for her safety?

I placed my Mother in Assisted Living about 9 years ago because of Dementia and Bipolar, she was evaluated at Spartanburg Regional after pulling up in someone's driveway telling the homeowner she was waiting on a plane to take her somewhere. After 2 weeks in the physc. ward there they told me of the diagnosis and so I began looking for a good Assisted Living Facility and finding one after 6 months.in the meantime I was giving all her personal affect and found where she had forgot to pay the house payments and the bank took it, Now se is saying that she can live alone and wants to leave even though the doctors notes plainly says she can not live alone and can no longer drive as well. I am her only daughter/POA...one for her medical and another for her monies which goes directly to the Assisted Living Place. Can you give me some advice as to what to do now? I have found a Phychiatry doctor and am now waiting for an appointment so I can only hope he will say she can Not live on her own. please help Linda Bulman