«كَمْ طَالِبًا حَضَرَ؟» — How many students attended?
كَمْ: interrogative noun; طَالِبًا: accusative tamyīz; حَضَرَ: past-tense verb.
Although ṭāliban is accusative, it is not the object of ḥaḍara, which is intransitive.
An accusative ending does not automatically mean “direct object”: here it marks tamyīz.