A couple more ideas...
Stephen Foster ABC
has lead sheets to several tunes with which they might be familiar. Even if they grew up with ipads in their hands, they've probably heard "Camptown Races" and "Oh! Susanna." Also shown here are Nelly Bly, Old Black Joe, and Angeline the Baker, which are super simple to play. Someone else mentioned "Turkey in the Straw" and they likely know that.
It might make sense to create a dubbed recording of several tunes such
as "Camptown Races" (my link has a MIDI file) and use that; the band
could play along or take their break. (MUCCy types might object to the use of recorded music. I've never gotten push-back from a onzie audience.)
While I've always enjoyed the challenge of working with a new band, and a new-to-this-type-of-dancing band, IMHO they should at least make an attempt to meet you halfway. (Some years back I removed a group from my Rolodex because, despite their fan base with potential clients, they would not respond to e-mails, phone calls, nor texts from me. They finally responded after our first mutual client nudged them. When I requested their availability for a subsequent gig, it was radio silence; after my second attempt in a week, I went with another group who replied promptly.)
I digress. Sometimes a booker's vision doesn't line up with reality:
--this band played for our wedding, surely for our anniversary party they can provide contra dance music
--this group is holding a jam session, and you're already leading a dance workshop; surely they can provide live music for your dance
--our church string band would like to play for the dance
For those following along at home, you'd request a tune list, then pick some tunes (perhaps creating some medleys), then provide them with Dance Band 101.
a musician as well as a caller