How do I confront my husband about his mother's attitude towards my family?

Over the past 3 years when our mothers have given us parties(i.e Wedding showers,baby showers etc.) inclduing my wedding, my mother in law does not greet any other guest but the people she knows. She does not even greet my mother at my daugther christing. My mother tried to speak with her about it, and she turned it around and stated to my husband my mother was rude and sarcatic to her. ( My mother asked her why she is not a good host and only greets her guest)