Get her one of those cheap mandocasters and change the strings to suit.
www.thomann.de

Harley Benton MA-500 VS Bluegrass Series
Electric Mandolin Body: Basswood, Neck: Maple, Neck attachment: Bolt-on, Fretboard: Amaranth, Fretboard inlays: Dot, Neck profile: Rounded V, Bindings: Cream-coloured, 20 Frets, Scale: 350 mm, Nut width: 28 mm, Double action truss rod, Pickups: 2...