Where do I get guardianship and POA?

You sit down with an attorney and petition the court to be her Guardian. As long as you have good credit and no criminal record you have a good chance to be appointed. A court evaluator will interview her and other siblings about her situation and ask them all if it is OK that you are her Guardian. If all agree, the Judge issues a court order and you get some training on how to handle the financial reports to the court.