Answer: He and I want to attend the festival tomorrow.
Explanation: "He" and "Him" as well as "I" and "me" are first-person personal pronouns which can be used to refer to yourself "I", or the third person "He" but each one is used for different cases. Grammatically speaking."I" is what is called a nominative pronoun, that it is used as the subject of a sentence whilst "Me" is an object pronoun, functioning as the direct object to the verb or as the object of a preposition. Similar case with "He" and "Him".