She was using a non-standard Apple charger. I have seen two of those blow up myself (as in the internal components were literally blown up, and the case was blackened). Assuming the cable was fried and the charger was in her bed, she would have been using an extension cord, which could itself electrocute her. There shouldn't be 220v output on the 5v output line, but those chargers are so crappy that anything is possible.

The only thing I don't get is why didn't the fuse blow?