If it was YEARS AGO, then WHY are you asking now?

Not exactly something every woman has on hand.
Tell you the truth I have no idea where the nearest shelter of that type even is.
To get one you would have to.. well I guess you would have to go to one and ask for the card?
I don't see anything wrong with sharing the number though.

I would talk to the MIL about it.
Since the aunt agrees with the MIL perhaps somewhere in the past, that they both know about, there has been some problem.