If you want to use your current subscription to itunes match, then her phone will have to use the same apple id to share that libray. But there are restrictions with associating a device to another apple id.
You can use home sharing, but her phone will have to set up with the apple id that sharing is set up with. This is great way of sharing, but only accessible from with the local network (your home wifi).
Home sharing support
Understanding Home Sharing
Really the best solution in my opinion, which will cause the least amount of problems, is to just import the same music into her itune library on the computer. This way she can use her own id on her phone, and just sync what she wants to, when she wants to.
Adding music to your iTunes library