The world is certainly not fair and good students sometimes are accused unjustly of an infraction of school rules. And there isn't always much in the way of due process for students. Rules in schools are not unlike rules in courts of law. Although you might be innocent...you could be judged guilty and punished anyway. So what do you do when your child has been suspended from school unjustly when it comes to the college application question: "have you been suspended"?
You have three options in such situations:
1) try to get the suspension expunged
2) treat the suspension as if it never happened
3) use the suspension as the most interesting college essay ever
Choosing options 1 and 3 allow you to deal directly with the issue and option 3 could actually work in favor of the student. Ultimately the decision is up to you. My experience is that students with minor issues don't suffer from answering yes if they clearly explain what they did, why, what happened, what they learned from the situation and how they will act in a similar situation in the future.