Mia didn't want to abuse the goblin's generosity and she attempted to pay him with a bone taken from the megalania. It was the closest thing to money she had since goblins went crazy for beast parts. But the goblin shook his head and wouldn't receive anything from her.
He was one of the many goblins that almost perished fighting the huge lizard and, even if he couldn't communicate it with words, he wanted to thank the person who saved him. If he knew Mia actually wanted the fabric to make a dress for Athela, the bad warrior who killed younglings without hesitation, he would have asked for proper compensation. In fact, he would have overcharged her.
By the time Mia went back to Ryu's house there was yet another pile of gifts waiting outside, goblins were truly grateful towards Ryu. She took the gifts inside and rummaged into them to find something that could be helpful.