What quest is the object Dravin's Bow from?
Solution 1:
What you picked up was a miscellaneous objective, Bow to the Master when you were in the Ratway Warrens.
To complete it, return the bow to Dravin. You can find him at the Merryfair Farm.
Solution 2:
You can also put it on any weapon display if you own a home and don't feel like doing quest yet.
Solution 3:
He is in MerryFair Farm directly west from riften stables, However if he is already dead (like it was for me) Then you can just place the bow on his body and take whatever you want as a reward from his corpse - I only took half his gold, im not greedy you know :)
Solution 4:
You can give it back to Dravin, a guy in a farm near the Goldenglow Estate
(an island where you have to go for a quest for the Guild of Thieves)
Actually I'm not sure if the guy is called Dravin. It is an elf working in a farm in front of the island where Goldenglow is.