I thought a red face/body means blood rushing?? Guess not because it like my mother who is currently in university trying to get a medical degree, isn't in university.

Blushing is just blood rushing because it is literally a fight or flight mechanism your body does when there is an emergency. Why are you 'blushing' though? Because your heart and breathing rates are increasing to keep you alive by delivering as much oxygen possible. Blushing is just a easier word for "blood-rushing" basically.