If it were me, and I've done this when faced with a similar situation, I simply say hello, and let it go at that. I figure for whatever reason, if I'm not worth their time, they're not worth mine.
I had a similar situation, at a friend's bridal shower. I had never met her MOH, and the shower was at the bride's parent's home. I knew the bride, and a couple others in our group of friends. But no one else. The MOH, the hostess, was not very pleasant at all. Didn't even come over to introduce herself, or even say hello. Just looked at me and my other two friends like we were dirt. Which I thought was rude, but I figured its her problem, not mine. Same thing at the wedding.
Subsequent to this, my friend the bride, has invited me to in home parties the MOH holds, and I decline every time. Mainly beacuse I don't those type o things, but also due to her rudeness at the shower.