Unfreeze the Elder with Hot Spring Water [which can only be obtained by pulling back the tombstone in Darmani's grave]. The Elder will teach you the intro to the Goron Lullaby. Play the intro to the Elder's son and the Elder's son will teach you the remaining notes. Then go back to the temple and play the Lullaby [you must stand between the 2 flags for the lullaby to work. Must be played on drums]