This is one of three main quests that will appear in your journal after helping the mysterious beggar, which means completing the "Mysterious Man" main quest.
Explore the town. You might find something interesting.
Rewards: Medium Bag x1, Lentils x10, Apple x5, Hernandian Attire
To complete this quest, you must head to Muckroot Ranch, located south of the city. Once you arrive, speak with the couple, Lauren and Arlan, whom you will find near the house with clouds of smoke billowing out of it. The woman will ask for your help cleaning the chimney.
Start by picking up the broom leaning against the wall of the house.
Open your inventory, navigate to the broom on the inventory side and equip it. Then use the wheel to select the broom.
Climb on top of the chimney, and while standing on it aim, look down and when the prompt shows up, clean the chimney.
After cleaning the chimney, you will automatically climb back down to the ground, where you'll receive a reward for your help. Among the rewards, you will find a new quest item, Hernandian Attire, and the quest will end.
A blocked chimney was the source of the commotion. You cleaned the blockage and received some fine attire as a reward.