Illegal Apartment By Manager?

My stepson just called from Los Angeles extremely upset. The manager (my stepson's dead beat dad) of the apartment where he and his wife and daughters live walked in on his wife without any notice at all. He did not even knock on the door or ring the bell. His wife was emotionally distraught when he suddenly entered with a master key while she was alone walking around in her underware. His excuse: " I was just bringing a card and a candle for my grand-daughter." My stepsons daughter is 2yrs old, can't read and her birthday is not until August . The manager is aware when my stepson is not home and they both feel very violated! Help!