Something Sentimental

Something Sentimental is a side quest in the Fallout 76 update The Legendary Run.

Walkthrough
The quest starts by traveling to Foundation and speaking with Maggie. Alternatively, one can enter Monongah Mine during the A Colossal Problem event and pick up a holotape entitled A father's goodbye, which will also lead to her.

She tasks the player character with finding a way to enter the mine for the purpose of finding any trace of her father, Earle. She mentions that a large explosion may pry the mine's entrance open. Another clue as to how to gain entrance can be found in the form of a raider's note.

In any case, the next step is to drop a nuke on Monongah Mine, triggering the event quest A Colossal Problem, thus gaining access to the mine's interior. This can be done by completing Mission: Countdown and launching a missile, or that another player nukes the mine. Afterwards you just need to join and complete the public event A Colossal Problem. Progressing the event quest results in the player character finding and having to kill her father, who has mutated into a powerful wendigo colossus. Afterward, one can find his pocket watch on his remains.

Traveling back to Maggie will conclude the quest by chossing one out of three different dialogue choices with different outcomes:
 * Lying to her that nothing was found allows for keeping the pocket watch. Requires +8 of Charisma.
 * Telling her that only the watch was found results in losing the watch and gaining 60 caps as well as ~300 XP.
 * Telling her the truth about her father's mutation and death results in losing the watch and gaining 60 caps as well as ~300 XP.