I agree with previous posters that confronting this mother will not do any good, and will probably just make the situation worse - she'll probably go so far as to call you "stalkers", like she does the member of the Evansville Bike Club. I'm sure there's little you can do to get through to her, so I would recommend continuing with what you're doing to reach those who are likely to hear the message. Your work to educate motorists and remind them to "Share the Road" is very commendable!