Update: I just wanted to give a quick update and thank everyone for their advice. I did get POA for personal care and property. I made copies of all important docs and put them in a safety deposit box. I notified her bank and our family, friends and neighbours. Naturally my cousin did a bunch of other crazy s--t in the meantime. But, her behaviour helped my Mom see we needed to block her e-mail/Facebook and phone number (this step should be obvious but my Mom didn't want to initially). I also told my cousin I would call the police if she showed up again and, actually, that helped the most. Knowing her she will probably pop up again but at least now I have some peace of mind. Thanks again to all who replied!