"The efforts of the central government in ensuring food security" is grammatically correct.
"Should be replicated in states that" is also grammatically correct.
"Are ought to fully implement the Act" is incorrect. The word "ought" already carries a sense of obligation, and "are" is unnecessary. The correct form is "ought to fully implement the Act."
"And reform their respective distribution systems" is grammatically correct.
Thus, the error is in option (3), where "are ought to" should be corrected to just "ought to."