Question about morphine dosing?

My mother was on 24 hour oxygen, a storm hit and she went on a portable tank which only lasted a few hours. She could not see and fell, I found her laying on the floor. She was awake and told me what happened, she didn't want the abulance to make all sounds and she was hurt. We went to the hospital, once they checked her over the dr gave her 2mg of morphine mom was 89lbs, had copd, asthma, and may have been hypoxia. Than they took her for xrays when she returned she was glossy eyed, unresponsive, and slipped into a coma. It that does too high? I can not seem to find any answers and hypoxia doesn't fit what happened. She went from talking and breathing ok to a coma and passing away all within hours. Any advice is greatly accepted.