Toward the end of his life, John Updike, who had been the voice of suburbia for four decades, turned away from middle-class angst and desire to explore darker matters. In his last published novel, “The Widows of Eastwick,“ Updike, who died in January at the age of 76, returned to the magic-wielding heroines of a previous book and found them robbed of youth, beauty and even, at times, hope.