Mama knew what was going on. I think she also influenced Vito more than we realize. My money says Mama is the one who came up with the "We don't discuss business at the table" rule.

I gotta go with the folks that said she knew her place and trusted her husband. I have absolutely nothing to base this on, but I think she told Vito her thoughts and/or concerns - she was just smart enough to do it privately.