Maggie becomes paralysed at the big fight. She loses a leg to bedsores, and then asks Frankie to end her life. He hesitates because of his faith and she tries to do it by biting her tongue. He then decides to do it by unplugging her breathing machine and then injecting adrenaline into her IV. After this Morgan Freeman tells Frankie's daughter in a letter (which was also the films narration) that he never saw Frankie again. And the last shot is of Frankie in the diner we saw earlier in the film.