A music degree is not just good for a career in music. Any good music degree will teach a raft of transferable skills - critical thinking, creativity, teamwork, reaerch and writing skills as well as meeting a bunch of interesting people to start building networks with.
The dominant narrative pushed by the government that a degree should be judged by the career that it qualifies you for is rubbish. If she's interested in music a music degree can be rewarding in itself and she's more likely to do well and get a good mark than in something that supposedly gets you a good job.
Not all music degrees are the same, some are conservatoire style where you focus on playing your instrument and becoming a professional instrumentalist, some are more generalised where you can explore and specialise in a range of musicology, historical, technology or even psychology related topics.
I did a music degree in the 90s (when it was still free) and Im know a technical manager. I use (non musical) stuff from my degree every day.
The fees these days mean that you will think really carefully and feel under loads more pressure on your choices.