Start: Go to the church in Lumbridge Castle and talk to the priest.

•  hermit's house is in swamp south of Lumbridge Castle
  -talk to the hermit. He'll give you the Amulet of Ghostspeak.
• Return to the church and go into the graveyard while wearing the amulet.
  - Now you can talk with a ghost
  
•  Skull can be found in catacombs under Wizard's Tower.
  - You can take a skull from a cell guarded by a level 21 skeleton.
  
•  Return to the ghost with the skull and place the skull in the coffin.

Reward: 1 quest point, prayer skill (+5[level 1-6])