+1 to the above, style and tradition is the big thing here. it would be more correct to play Medtner as a 'romantic' selection and include some other 20th century/modern piece that it would to include a romantic piece and then also the Medtner as a 20th century /modern style work.
Have a look at some of the more conservative 20th century composers if you you have trouble connecting to the style, ie Elinor Remmick Warren, Nicolas Flagello, John La Montaine, Samuel Barber to name a few Americans.
Also consider maybe David Diamond, Norman Dello Joio, Leonard Bernstein, Seymore Bernstein, Louise Talma, Robert Starer, etc. for more meat in the space they are asking you to demonstrate.
ie this is particularly lovely
can suggest more later, but parting sugg....Poulenc nocturnes, are super groovy, have a looksey
