What evidence is there that the grandmother would be PVS or comatose were she not massively drugged?
Evidence? None that would please you.
There was a massive amount of evidence in the Terri Schiavo case. Doctor after doctor. Report after report. Evaluation after evaluation. Ruling after ruling.
Not good enough for you. You insisted on one more test. One MRI. One PET. One more doctor. One more evaluation. One more (de novo) trial.
There is no such thing as evidence that will satisfy you. I won't waste my time.