After looking up some followup articles and audio, she died of a heart attack. While at first this might sound bad for the fam, it explains a lot. She wasn't dependent on the oxygen, but without it she was probably at a fiftyfold risk for having a heart attack. That explains why there was a 2 hour lag. The family has a limited education. The health care system tends not to blame people with limited education for bad moves, such as not going to the hospital immediately when the power went out. A lot of people are probably going to say that's bullcrap, but social and education levels are a very complicated thing when it comes to healthcare. Instead of blaming them, healthcare tends to blame itself when people make dumb health decisions like the fam did that day, since it was the healthcare system's jobs to explain to the family these issues.
Even if the family was being too overdramatic with the power company, the stress of the power outtage plus the lack of oxygen to cover the spread almost surely induced the heart attack.
The electric company admitted wrong by undergoing some samoan apology ritual from what I've read. They're paying for her funeral and entering into compensation talks.
Editing: This is going to draw some flak I'm sure, but according to some of these articles she was on the breathing machine for respiratory trouble tied to her obesity. The breathing machine was indeed not intended as a life support. As such, the claim that she "needed" the oxygen to live was false, but that doesn't change the almost sure fact that the power cut led to her heart attack and that without such cut, she would be alive.