During the quest The Ghost Haunts at Midnight pick up the diary located on a steel counter in the kitchen to begin the quest.
After using the food-lift in The Ghost Haunts at Midnight pick up the diary on the left hand side as you exit into the kitchen.
Continue through the hotel as you would normally for the above quest. You will collect the pendant at the end which is used for this quest as well.
Decide to give the pendant to either Jeanette or Therese.
Jeanette will be immediately available after returning to The Asylum.
Therese will appear at The Asylum after completing the quest Slashterpiece.
After Slashterpiece is concluded one of two outcomes will be presented for this quest
If the pendant was given to Jeanette she will have thrown it in the ocean thus failing the quest and leaving the ghost trapped.
If the pendant was not given to Jeanette it can now be given to Therese. This will allow the spirit to be freed and the quest to be completed successfully.
This section is incomplete and requires expansion.
Update: Upon receiving quest:
You have discovered a journal in the Ocean House. According to its contents, a jealous husband murdered his wife and family because of a locket. The murderous ghost of the husband means to keep her trapped here forever with him, and she seems to be trying to help you find a way to free her.
Update: Speaking to Therese after giving the pendant to Jeanette:
You have trapped the ghost of the doomed woman in the Ocean House with the murderous ghost of her husband for all eternity by letting Jeanette have the pendant. Now it allegedly rests at the bottom of the ocean, somewhere, never to be found.
Update: Upon Completion:
By delivering the pendant to Therese, you have given her the means to free the spirits from the Ocean House, thereby delivering the unfortunate wife to her eternal reward and her murderous husband to his eternal damnation.