Audition piece?

The daughter of a friend is going for an 'interview' for a place on a drama course at Edinburgh Uni, and as part of it she's supposed to prepare a song, which will be accompanied by piano. She's a bit thrown by this as they've provided no guidance as to what type of song, music, etc, and apparently the relevant office that might explain it is closed for Easter up until the day before her interview. Do any of you have experience of such things / family members, friends etc who've done it, who can shed a bit of light on what sort of thing they're probably looking for?