Rewrite the sentence in indirect speech.
Nisha said to Sunil, "I will not be going for the class."

Correct option is C

The correct option is (c) Nisha told Sunil that she would not be going for the class.
Tense change: "Will not be going" (future continuous) changes to "would not be going" in indirect speech.
Pronoun change: "I" becomes "she" in indirect speech.
Time clause change: No time clause change is required.
Reporting verb change: "Said to" changes to "told" in indirect speech.
Corrected sentence: Nisha told Sunil that she would not be going for the class.