Myrlie Evers-Williams moves gingerly about the crowd, slowed by her 80-year-old knees. The University of Mississippi chancellor, who has invited her to speak at commencement exercises, takes her hand to lead her down a flight of stairs. Students, black and white, ask to pose for a photo with her as she makes her way to the stage. Her daughter, always nearby, is holding her purse. She is doted on.