Answer: It means there is an end to everything, nothing is permanent and nothing is forever.
Explanation: Every single living organism has a beginning and an end, it's only a matter of time. Just like the day we were born; we will surely die one day and every single riches and fortunes we have saved up becomes meaningless to us (the dead don't use money), Only our kind heartedness, our charity and everything good we did during our lifetime becomes valuable to us, all other things are vanity and meaningless.
The answer is c because the subject is the topic of the story pretty much like if I where to write something about myself I would be the subject and let's say the theme is about bravery and I have to deal with that so yeah C
The speaker comforts himself into believing that the tapping sound is a visitor who has come to see him.
Hope this helps :)