Something Sentimental

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

Walkthrough
The quest is started by travelling to Foundation and speaking with Maggie. Alternatively one can enter Monongah mine during the A Colossal Problem event and pick up A father's goodbye, which will also lead to her.

She tasks the player with finding a way to enter the mine for the purpose of finding any trace of her father Earle. She also hints that a big explosion might pry the mine's entrance open. Another clue as to what to do next can be found in form of a raider's note.

In any case, one is required to personally drop a nuke on Monongah mine as the next step, triggering the event quest A Colossal Problem and thus gaining entrance to the mine's interior. Progressing the event quest allows for finding and defeating her father.

After defeating Earle, one can find his pocket watch on his remains.

One can then travel back to Maggie to conclude the quest with different outcomes:
 * Telling her that nothing was found allows for keeping her father's watch.
 * Telling her that only the watch was found results in losing the watch.
 * Telling her the truth that her father has become a man-eating monster results in losing the watch and only awards experience.