for music2, you have to do a piece from the last 25 years (australian focus). with your other 2 performance elective pieces: 1 has to reflect your additional topic, the other can be either another piece from last 25 years, or from your additional topic as well.
for music ext, the only compulsory thing is an ensemble piece. all pieces can be from whatever period you wish.
that being said, if you can show a wide range of periods, it would probably come off as more well-rounded and interesting to listen to. (mind you, the examiners can get bored after hearing 6 pieces!)