You are not clear on what specific music service you want her to listen to. If it's your Amazon Prime Music or Amazon Music Unlimited, this link should help with all the options available through Amazon for listening to music.
https://www.amazon.com/b/ref=nodl_?ie=UTF8&node=15730321011Even without a Prime account, just a free Amazon account, she can also listen to music through Spotify, iHeartRadio, SiriusXM, and Pandora. Some of those other music services offer free music options.
If you share your account, or create another household user for your Prime account (which is technically supposed to be at the same residence), be aware that some events activate all the echo devices on that account (calling, intercom, etc), so if for example you announce "dinner", her echo would also make that announcement. Plus, be aware that she would then have access to your credit card information for ordering from Amazon, so you would need to be ok with that, or set up restrictions for ordering from her echo device.