In this sentence, the correct pronoun to use is "I" because it is the subject of the sentence. Therefore, the correct choice is "Amadi and I." The sentence should read: "Amadi and I went to the stadium to watch a football match." Using "me" as in option C or "myself" as in option D would be incorrect because they are object pronouns, and in this context, "Amadi and I" are the subjects of the sentence, not the objects.