How do we convince my mother to move to Assisted Living for her own safety?

Mother's dementia as well as hallucinations are causing us to fear for her safety living alone. Every time we bring up the subject she refuses to listen and storms out of the room. In the past couple of weeks she has had several hallucinations. She is Biploar and Borderline Personality Disorder. The last episode was scary enough that I thought she had "checked out" permanently. We really need to get her into Assisted Living. Any suggestions on a way to convince her? Thank you so much for your suggestions and help!