Mourners packed Temple Emanu-El yesterday to bid farewell to Ethel LeFrak — the beloved mother of prominent developer Richard and his sister, Francine — who died Tuesday at 93. Francine recalled at the service, attended by 1,400, that Broadway great Brian Stokes Mitchell came to visit Ethel in the hospital during her final days and sang to her by her bedside. “Ethel loved ‘South Pacific,’ ” explained a guest at the service. “Brian came to the hospital and sang ‘Some Enchanted Evening’ to her, and Ethel even mouthed the words along with him.” Mitchell performed in a concert version of the show at Carnegie Hall. Ethel died on what would have been her 72nd wedding anniversary with late husband Samuel.