You can help Reeky defeat the attackers or leave him behind and run away. You spent a lot of time on searching for Reeky - the man is gravely injured. The bandits won't appear but Reeky can't be saved (you can only end his suffering by killing him mercifully).

How long do you have to find Reeky?

On the Scent is the eleventh main quest in Kingdom Come: Deliverance. It begins automatically upon completing Mysterious Ways, when Henry learns about Reeky of Ledetchko. This is a timed mission, and taking too long - more than about three days - will ensure that Runt reaches Reeky before you do. You will need a spade.

What mine shaft is Reeky in?

After heading back to Rattay and selling goods at town, resting up, and making yourself presentable, it's time to track down Reeky. He's hiding out in Ledetchko, just North of Rattay Mill.