You will almost certainly have recourse under your by-laws about people not disturbing the peceful anjoyment of others lots. Get the EC to shut the drummer up and move him on. There are plenty of rehearsal spaces available.
And don’t hold back – installing a drummer in a strata development is the absolute height of selfishness.
If she’s so worried about junior’s career in music, your neighbour can shell out for electronic drum that only he will hear.