Well maybe she got a bit frazzled when all this happened, but it sure sounds like the engine just quit running. My feeling is that we always accept the simplest answer first before going off into the esoteric realm=== and really, an engine stall fully explains the symtoms.
If the fuel pump relay failed, the oil pressure switch would have powered the fuel pump anyway (in theory).
Anyway, you could squirt some starting fluid into the intake system to see if the engine runs momentarily. If it does, then you must have some fuel delivery issue. You could use a fuel pressure gauge to test pressure in the fuel rail, and you could check the fuel pump relay. Sometimes if you read the part # on the relay you can find another one in the array to switch off with that one, for testing purposes.