My Boyfriend is now Illegal?

I need advice from anyone who knows about these things. I am also worried about the legality of our child. My boyfriend is 22, and as far as I know, a legal citizen. He workes a normal job, files taxes and attends the state university. Today he called me frantically saying something serious happened. His mother was apprehended by the police, and did not have her citizenship card. She is right now in custody. My boyfriend says that she now has no proof she is a legal citizen. She also owns a home and works a state job. She was not born here, but gained citizenship. My boyfriend is saying because she has no proof of citizenship he now has no proof either. Does this add up? He's worried about our child and how that affects her. I was born here in the us and so was our child. Can someone explain how this works? My boyfriend is very worried and so am I. Thank you!