Was your Mother in a PVS? I'm sure she wasn't if she "asked" for water.
She was diagnosed as PVS for six months. SHE WASN'T. She had dementia, and could barely speak - The doctors said to pull her feeding tube, that she'd never come out of it. She battled back to 140 lbs from 84 and held her first grandchild in her lap, even though she couldn't speak.