How did his dad died?

Eddie's father died of pneumonia.

"That was how he took ill, of course. He lay there on the beach for hours, soaking and exhausted, before he had the strength to struggle home. Your father was no longer a young man. He was already in his fifties." '

"Fifty-six," Eddie said blankly.

"Fifty-six," the old woman repeated. "His body had been weakened, the ocean had left him vulnerable, pneumonia took hold of him, and in time, he died."