Can I get information on my father's condition even though my mother has instructed against it?

My father has recently undergone a total knee replacement. He is 82 years old with type 2 diabetes. He had had acute renal failure due to complications from the surgery. He is now in a rehabilitation place. My mother is not keeping any of the children informed as to his condition and furthermore she is not keeping an eye on the signs of acute renal faliure. She is more concerned with being the center of attention. She has now instructed the re-hab not to give any information out regarding my father. How can I get this information or have her declared mentally incompetent before my father dies? Please help me so I don't lose my father.