I have been reading the various posts that say the MOB should have her shoulders covered and not wear a strapless gown, is this only for the ceremony? Would it be proper for the MOB to wear a business suit to the ceremony 12:30 and a evening gown to the reception 6:30?
If the real question is if you can wear a strapless gown to the reception, the answer is still "no". Mothers do not dress to draw the eye. Red is also a no-no.