Give Charles some food.
Go to the house with a green roof in the west part of Coal-Mining Town to find Charles lying of the floor. Talk to him to activate th event.
Go to the bridge in Pipe Area to find Bananas next to the leftmost chain. Grab it and return to Coal-Mining Town. Now you need to make some Baked Bananas by inserting the bananas into the machine in middle of Underground Machine Room in order to get it.
When you have acquired the Baked Bananas, go back to Charles and give it to him. The event is cleared.