A 39-year-old man was arrested Sunday after he assaulted and robbed two women he held hostage at a home in Atlantic City, authorities said. Justin Williams threatened to kill both women with a knife before beating them and stealing their property around 9 a.m. in the residence on the first block of north Georgia Avenue, Atlantic City police said. He also allegedly tried to throw one of the women out a window. One woman had escaped when police arrived. Williams, of Atlantic City, later surrendered. Williams was acquainted with both of the women, police said. He was charged with two counts each …