Is she needs a morphine drip to ease her pain, wouldn't that mean, then, that she is not totally brain-dead? If she were truly vegetative, wouldn't she even feel or be aware of anything? That alone makes me question the right to remove the feeding tube.
(Sorry if this is naive, but I know zilch about physiology, let alone health care.)
Taken orally, the effects are felt more gradually. Physical effects include nausea, vomiting, insensitivity to pain, contraction of the pupils, increased urination, constipation, sweating, itchy skin, and slowed breathing.
With very large doses the pupils contract to pinpoints, the skin is cold, moist and bluish, and breathing may slow to a complete stop resulting in death
I think this is why morphine has been given. Not out of a kind heart to ease her suffering, but to hasten Terris death.