Since B got the ball before they fouled they could retain possession if they declined A's facemask foul. However, since B had possesion of the ball in their EZ and fouled there, it would be a safety. Therefore, depending on the score B might want to accept the facemask foul, hence creating a double foul and offsetting and a replay of the down.
Point of discussion: I believe the above is by rule and yet we recently discussed the theory of this (on this forum or another..don't recall)since B did not force the ball into their own EZ then the enforcement spot becomes the 20. In that case they would certianly decline A's facemask and keep the ball after being penalized for the illegal block. 1st and 10 for B on their own 10
I like the 20 yd line being the basic spot in this case...but thats just me...
It is very late here, so correct me if I am a bit sleep deprived
