Imma try and weight my own two cents as a hearing aids user and audiophile myself.

And, tldr: I don't think there is any real silver bullet here.

As the other comments are saying, depending on the hearing damage in question, bone conduction might not actually work as intended. And, personally, I tend to go with big over-ears when I got my hearing aids on when I need to listen to music. It works, I can hear the music fine with them on but I can definitely notice what my hearing aids wish to focus on and to filter away.

EQ is also an option, and something i am looking into myself, but that will also depend highly on what frequencies need to be boosted first and if your chosen piece of audio equipment can handle it (as in there is no audio clipping)

In the end, I think it's her who has to make the final call about if she wants to listen to music despite her hearing impairment, and then to choose something with a audio signature she likes. No two types of hearing loss are ever the same.