“Man is least himself when he talks in his own person. Give him a mask, and he will tell you the truth.”
Here, it means that people are afraid to reveal truth in person to the public, as it might affect his/her social status, identity, etc. So, people would reveal the truth anonymously. I think Wilde is criticizing the typical nature Victorian England’s society, which is even true today in the society we all live in.
“All women become like their mothers. That is their tragedy. No man does. That’s his.”
Wilde is criticizing the feminine and masculine roles assigned to men and women, by the Victorian society. This quip has a certain double meaning. It doesn’t really mean,