"Hurley's Coronation" is an orchestral piece from the Season 6 soundtrack. It's plays during the finale.
Hurley looks at wounded, silent Jack and realizes he plans to die after relighting the Heart. Jack tells him that having fulfilled his destined responsibility as protector, he now must hand the job to Hurley.
Ben offers an Oceanic bottle, and Jack fills it with water from the river. Hurley drinks it, and Jack inducts him as his successor.