I'm very sorry to hear of your mother's situation. I checked, and it is important that the following are done. It would be good to have the operation, but you need to do the following immediately:
- Medicine Buddha puja by Bati Khamtsen at Sera Je Monastery. I have sent the request to them already.
- Lu-zong: Ask the geshe at your center to do it.
- I will do a puja for her today.
- Tonglen practice: I and others here will do this for her and you also.