M.P.
I notice that no one has addressed your question of which to do; monitor every 6 months or try meds with a 5% cure rate. I'm not sure what you mean by cure rate. And is your mother's hep b in remission now?
Based on my several experiences with monitoring I'd recommend the monitoring. 5% seems like such a small amount that it doesn't seem worthwhile to me if your mother's illness is in remission. She would still have to be monitored. Meds have side effects which I would consider before taking any medication.
I wonder if there could be some other cause for her pain. I have had abdominal pain, including some in the region of my liver. My pains did start when I was young. Eventually I had exploratory surgery which revealed that I had endometriosis. Endometrium, the uterine lining, can migrate throughout the body and cannot be seen without surgery. Especially if your mother had pain with her periods I would consider that a possibility. Even tho I've gone thru menopause I still have some abdominal pain. The endometrium still responds to changes in hormone levels which continue to happen.
Another possibility is a sprained or strained muscle. I get a pain in my lower left side which does not seem to occur with any particular activity. I've had numerous tests, including those for heart difficulties and a CT scan and the doctors have suggested that it could be a muscle or adhesions from surgery.
Pain, especially when we have dealt with a serious illness, is scary. I've found that I have to accept that I have pain without knowing it's actual cause. It is easier for me to do this now that I'm in my 60's because I've "survived" many times when I worried about serious possibilities that never occured.
I hope that you and your mother are able to find peace with whichever decision you make.