I want to let players in a game that I organize search for the treasures that the master of Lake-town took when he left. Is there the possibility that he hid them somewhere before he died? Or does Tolkien mention somewhere explicitly what happened to them?
We don't know what happened to them. We learn about the Master of Lake-town's flight on the last page of The Hobbit.
The old Master had come to a bad end. Bard had given him much gold for the help of the Lake-people, but being of the kind that easily catches such disease he fell under the dragon-sickness, and took most of the gold and fled with it, and died of starvation in the Waste, deserted by his companions.
“The Waste” could be anywhere outside the few inhabited areas besides Dale, Lake-town and Erebor to the north-east of Mirkwood.
This doesn't come up in The Lord of the Rings. I don't know if Tolkien left notes about this matter, but I doubt it, as the theft of the treasure is narrated to characterize the Master, not because it's important for the plot.