In 1948, when the cinematic version of her story, “Gentleman’s Agreement,” received the Oscar for best picture, Laura Z. Hobson was a 47-year-old, divorced, Jewish single mother living in Manhattan. The success of “Gentleman’s Agreement,” which was serialized in Cosmopolitan in 1946, published by Simon & Schuster in 1947 and produced as a film by 20th Century Fox later that year, had made Hobson into a wealthy and famous woman.