Answer:
He had limited success because he was a generally nice person without a surplus of ego and because he wasn't flashy.
This happens when Ruby becomes disappointed with Tom when the hose leaks and Ruby can no longer dive. The two stop hanging out, and Tom loses her friendship.
The light, then, is the light that her friendship brought to his life. Her friendship is light -- it is happiness and is joy to Tom. When the two friends stop hanging out, the light goes out of the marsh. The author is saying the joy has gone out of Tom's life.
I think this story is told in a witty an interesting way since it started where it should have finished with the funeral of the main character to create intrigue. Emily was somehow weird when the story said that there was hair on the pillow which meant that she slept next to him when he was dead.
