“The fathers/husbands are responsible for the spiritual atmosphere of the family. They should be very involved. There is also the not so small matter that they, for the most part, fund the purchase of the clothing that is not acceptable, hold them accountable.”
First of all, not all families follow the man-breadwinner woman-homemaker model. It used to be that more yeshivish families were MORE likely to use this model, and now, as more men are being encouraged to learn full-time, even yeshivish women are taking on responsibilities of parnassah. Therefore, the clothing may in many situations be funded by the woman’s work, not the man’s.
Second of all, and more importantly: I can’t speak for anyone else, but I’ll gladly tell you what my family’s response to this situation would be. If someone in shul (it really doesn’t matter who) approached my husband (it really doesn’t matter how) to tell him that I was dressed inappropriately (it really doesn’t matter if I was or wasn’t) it would lead to feelings of anger and resentment from both of us, possibly a fight between us, and we would almost certainly switch shuls. So if your objective is to get these people to leave the shul at all costs (because after all it’s “not a nightclub”, and there is nothing in between dressing appropriately for a night club and dressing inappropriately for shul), even if it means causing some damage to shalom bayis along the way, then by all means speak to the husband/s.
Now, if the rebbetzin were to speak to me privately and gently, in a way that made me feel humbled and welcomed and wanted, I would be very embarrassed and very grateful to her. I would immediately change my mode of dress. I would continue to attend the shul and hold my head up proudly in front of the rebbetzin, feeling like I belonged. And I would NEVER tell my husband what had happened, knowing that it would offend him more than it had offended me.