mate...
I honestly don't know...
Maybe learn a song with finger picking in it?
It depends what they are looking for really...
I would say probably somthing in a hard (unusual) scale
some fingerpicking maybe, key changes...timing (not just fast but slow...possibly time changes)
hahaha just some ideas

They might want to see how well you understand music...not what you can play and make sound good....to be honest they could be looking for anything so I would say play somthing that you are comfortable with.

hahaha ill try and think of a peice you could listen to....cant think right now