How can estate planning help protect mom's estate and provide for her care now and in the future?

How can I avoid possible problems with a brother who has not participated in caring for my widowed mother's care and financial management to date, but is now advising her by phone regarding her home and finances? He lives out of state and has suddenly become very interested in her affairs. She has dementia and is residing in an adult family home since she is no longer capable of caring for herself. I have been modestly rennovating her home which has been long neglected while she lived there. This is her biggest asset and will have to be sold to finance her continued care. We are the only siblings and I have been expending all the efforts to facilitate her care and managing her financial affairs. My brother is financially needy and continues to call her suggesting that her home be placed in his name. What steps can I take to protect her estate to provide for her care now and in the future?