If she likes historical music at all, or would like to explore it, the 17th century has some especially fabulous professional female composers:
Francesca Caccini (1587-1640): as a girl, she was part of her father's group of virtuoso singers and participated in some of the first operas. Later, she was the highest-paid musician in the Florentine court (one of the top jobs in Europe at the time), and was the first woman to compose operas. We still have one of those (La liberazione di Ruggiero dall'isola di Alcina), and it's a great story of an epic conflict between two sorceresses, involving lots of magic singing trees and sea monsters. And the male lead is a captured enchanted knight who just sits there waiting to be rescued. AND there's a horse ballet! She was known for her intelligence and talent, and she was a great advocate and protector for her girl students, against inappropriate advances by men of the court.
Barbara Strozzi (1619-1677) was the most prolific composer of printed secular music in Venice. She was the illegitimate daughter of an influential poet and intellectual, who made sure that she received the best training and opportunities available. She was an unmarried mother of four, and published her own music under her own name, without any court or church patronage. Her cantatas, mainly written for female voice, are amazing, colourful, dramatic pieces, that were at the cutting edge of composition.
Both of these musicians were swept under the carpet by later music historians, who weren't particularly interested in the activities of women. But in the past few decades, we've rediscovered their music, and it's finally starting to get the attention it deserves!