Did the MEL allow her to dispatch or not? It's a very simple question.
The Captain still has the absolute right to not accept the aircraft even if it is in the MEL - in fact all the MELs I have seen iterate this fact in the preamble. The Captain might deem that a certain combination of defects on that particular flight is not acceptable.
The operator may not agree but that's another matter.
I imagine these crew members might have a case against the Company for harassment/bullying?