Should I do a contract or Power of attorney to act on my mom's behalf.

I recently assumed my mother's care. She could no longer live alone and my brother said if I did not take her he would put her in a nursing home. My mom did not want to go to a nursing home so she lives with me now. She suffered a stroke and requires more care, hence, affecting my ability to work outside of the home. My mom gives me money on a monthly basis which I need to assist with the additional cost of her care, but at the same time I dont want her savings to dwindle. Her home in Miami where she can no longer reside is slowly taking her savings. Her bit of savings need to be for whatever happens to her in the future with her medical costs. I also prefer to draw a contract stipulating amt of money on a monthly basis esp. since I rather avoid any future dealings with siblings because they want to manage the money matters but nobody wants to assume her care. What should I do?