Ah, she mentioned three different bikes in rapid succession and I got mixed-up. Oops! It's easy to do.

Anyways, if the bike is to get a true cassette in 7-speed, there are quite a few that could do the job about as well: 14-32, 13-30, 13-34, 13-28...

If it's actually a freewheel, options are a little more limited, but 13-28 and 14-34 are both widely available.