Escort card question

I keep debating this...

We have a few guests who are single and flying solo.

Ms or Miss on the escort card?

My original inclination was Ms and I'm not sure why but now I'm thinking Miss is more formal.

Thoughts?

Ms if they are over 18

Miss if they are under 18

I agree on the 18 cutoff for Miss to become Ms.

And another example is always go with your gut!

Thanks girls! We don't have any under 18 except for the flower girl so that's easy!