Ghoul Problem

Ghoul Problem at (Location Name) is a Minutemen radiant quest in Fallout 4.

Detailed walkthrough
This quest can be started randomly when speaking to Preston Garvey, listening to Radio Freedom, or talking to the settler "in charge" of the settlement.

Failure to kill the targeted ghoul in a timely manner will result in the failure of the quest.
 * 1) Listen to the radio, talk with settlers or talk to Preston Garvey to get the quest.
 * 2) Speak to your contact in the settlement.
 * 3) Clear the ghouls from a random location. The Sole Survivor only needs to clear the targeted ghoul, usually a glowing one, to complete this objective.
 * 1) Return to the contact in the settlement and inform them of your success.
 * 2) (Optional) If the quest was started with Preston or Radio Freedom, return to Preston Garvey. If one decides to skip this step, the experience points will not be earned right away but a couple days later, when the quest is supposed to expire.

If the settlement is already under the player's control then the player will receive 100 caps as a reward, else he will win the control of the settlement.

Bugs

 * If the player character is sent to kill the feral ghouls at Fiddler's Green, a quest marker may not appear. Killing all the feral ghouls in that location may not update the quest.  If this occurs, allowing time to pass until the quest fails may be the only way to complete it.

Same problem as above at Super Duper Market