I can help you with the rewrites of the sentences provided in the question. Let's address each part one by one:
a) Rewrite the sentence:
"Nepal is a culturally diverse country where one can enjoy an example of tolerance and understanding among a number of castes and creeds."
b) Choose the correct verb:
"The class monitor, as well as his friends, usually perform well in the extra-curricular activities."
c) Choose the correct preposition:
"The thief escaped through the tunnel that was buried about five feet beneath the surface."
d) Choose the appropriate modal verb:
"Who is that man with Pushkar?" "I'm not sure. He might be his father."
e) Choose the appropriate form of the verb:
"Please, do not call me between 8 and 9 a.m. We will be having dinner then."
Identify and correct the grammatical error:
Yubaraj said that the document was personal, and he wouldn't let me read it.
These are the revised sentences based on the instructions given in the question. Let me know if you need further clarification or assistance!