When you use Aap when talking to a group, you use "hain", as you have, lekin (but) if your using Aap when talking to just one person and using it to show respect, you may use either "hain" or "ho" depending on how formal you want to be. Consider this; Aap Ho: Used with superiors, but shows a little intimacy, ie ( you know the person, mostly used with parents. Tum Ho: When you use this, you show neither respect nor disrespect, it is best used with colleagues). Tu Hai: This should only be used with someone you're sure wont mind, as it can be derogatory, I only use it with two or three of my closest friends. Hai is equivalent to (is) in English, and you will encounter it in most of Urdu sentences.

Its in hindi : tum hi ho tum = you , hi = only , ho = are literally will be = you only are ... logical one will be : only you. So far, i didn't fine (hi) in Urdu.. only hai/hain you cant always find equivalents in English.. hope that answers your question.