The only noun I know derived from the verb to entomb would be the noun entombment. It is an abstract noun, which means that it doesn't have a physical shape - you cannot touch it or smell it, just like with love, or hate, or happiness. Entombment is the process of placing a dead body into a tomb, or a grave.
Explanation: The first two quotes used show Walsh's apprehension about the people turning themselves in, and the last confirms that this apprehension is because of bad past experiences.
The answer is C for both because they follow the correct syntax and conventions of english to allow the reader to effectively read the sentence without confusion.
