How To Treat Brain Dead Condition After A Surgery For Hematoma?

A 84 year old lady fell out in the street taking her clothes to the cleaners and it diagnosed after what seems to a successful surgery of diagnosed hemotoma two -three days later that she is brain dead when all of her body functions are working except she is not talking and one doctor has said that she is brain dead; his results from one test. ? Is this enough time and testing to determine this when all body systems are working including she is moving her legs and blinking and all oher systems are still working?