What killed billy bones in treasure island?

In "Treasure Island," Billy Bones dies from a combination of factors, primarily due to the consequences of his past life as a pirate. He is plagued by illness, exacerbated by drinking and stress from being hunted by old shipmates. Ultimately, he suffers a stroke after being confronted by the menacing characters seeking him, leading to his demise. His death reflects the themes of guilt and the inescapability of one's past.