RutgersPIKE,
Maybe your chapter could have a "Parents Weekend" where you invite all the parents of the actives and pledges, have a nice barbecue or even a sit down banquet depending on your budget. You could do a slide show that shows your brotherhood and philanthropy. Maybe intercut it with clips of brothers talking about what Pike means to them.
Then you could do some sort of appreciation skit for the moms, grandmas, whoever else attends and give them a rose or whatever the fraternity flower is.
You gotta get moms at their hearts -- they cry when you start kindergarten, they cry at assemblies, they cry when you start college, when you get married, etc. But they ESPECIALLY cry when they are appreciated.
I'm tellin you.... a rose and a tear-jerking song and she will never give you a hard time again.