NIMCET 2022 — General English PYQ

The best expression of the sentence in indirect speech is (c) He said that he was glad to be there that evening because it correctly changes the pronoun "I" to "he," the tense "am" to "was," and the time expression "here this evening" to "there that evening". 
Here's a breakdown of the changes:
Reporting Verb: The reporting verb remains "said". 
Conjunction: The conjunction "that" is used to introduce the reported clause. 
Pronoun: The first-person pronoun "I" is changed to "he" to refer to the speaker. 
Tense Change: The present tense "am" changes to the past tense "was". 
Time/Place Adverbials: "Here" becomes "there" and "this evening" becomes "that evening" to reflect the shift in time and place from when the speech was originally made. 
Let's look at why the other options are incorrect:
(a) He says he was glad to be here this evening. This option incorrectly uses "says" (present tense) instead of "said" (past tense) and does not change "here this evening" to the appropriate "there that evening". 
(b) He said he was glad to be here this evening. This option fails to change the time and place adverbs "here" and "this evening" to "there" and "that evening". 
(d) He asked he is glad to be here this evening. This option incorrectly uses the verb "asked" and does not change the tense from "is" to "was".