Morphine is administered at the end because it depresses the repiratory drive, leading to high CO2 build up, and the cessation of breathing. It is usually done through an IV slow drip. It is done to help terminal patients at the end of life, never to murder a severely handicapped person as in this case.
Further thought: They are giving her the morphine by nebulizing it into a vapor from what I understand, since she doesn't have an IV. Thank God she doesn't have to feel injections, but it does mean that she is being gassed to death in addition to the starvation.
In their care was a gravely disabled female, who was not terminally ill, for whom they began depriving of food and water.
At some point it became apparent that she was terminal because the starvation and dehydration was killing her.
So when she officially became "terminal," they began to administer morphine to her to help her die faster.
America, watta country!