Have the Stalchildren open the grave and you enter some small chambers. In the first chamber, all you have to do is destroy all of the keese. This looks like it may be tough, but it isn't. Just keep slashing all of them with your sword. After you defeat all of them, a treasure chest appears with 50 rupees in it. Now enter the second chamber. If you played Ocarina of Time, you will recognize who this enemy is. It is an Iron Knuckle. Watch out for it's ax! It is very strong! Get hit and it will take away some health. To get a hit, wait until it swings its ax and it gets stuck in the ground. Now hit him! Rpeat this process. After about 6 hits, its armor falls off and it gets much quicker! Lay a few more hits on him and you defeat him. Now, Flat the composer appears. He then tells you about his brother Sharp, that is at the mouth of the river at Ikana Canyon. Next, he teaches you the Song of Storms: A, C-Down, C-Up, A, C-Down, C-Up.
Night 2-
In this grave, you can collect a piece of heart, and the Lens of Truth is needed. So look for a hidden passage way in the first chamber, and exit through that. Now, use the Lens of Truth to see a hidden ledge to get across. Then use a bomb to blow up the crack in the wall. Now enter the next chamber, and you face another Iron Knuckle. Defeat him to get a piece of heart. You can use the Song of Storms to slow him down this time.
Night 3-
In this last grave, you can get the last empty bottle. All you have to do is lead him to the six circular patches of dirt so he can dig for treasure. No, you aren't looking for buried treasure, but you are looking for three blue beams of light. One is on the main floor and the other two are on the second floor. To get Dampe up there, take him to one of the square platforms, and run up to the next level. Then lead him to the patches again and let him dig. Once you get three blue beams of light, you have to fight a Big Poe. Defeat it and you get the last bottle. You are done with the graveyard events now!