It's unusual to have that many lumpectomies, but rest assured that the surgeon is doing the right thing for your mother. Usually a mastectomy is recommended if they can't get clear margins around the tumour. Is radiation under discussion? Lumpectomy followed by radiation is regarded as the Gold Class treatment for early breast cancer.
Regarding the bilateral mastectomy there are many things to be considered including feeling of numbness on both sides instead of one, possible interference to the lymphatic system and the risk of lymphoedema especially if any lymph nodes are removed and the necessity to deal with two sets of drainage tubes (short term only).
If radiation is under discussion, most plastic surgeons would like this to happen and skin recover before doing the reconstruction.
On the positive side of a bilateral mastectomy she will be freed of having a yearly mammogram, often hard to pick up anything in women with dense breasts.
Is her cancer hormone positve? HER-2 positive? Triple negative? This is what will determine her treatment after the mastectomy and also who will treat her.
You need to find out these answers from your breast surgeon, plastic surgeon, Medical Oncologist and Radiation Oncologist before committing to any treatment. If you don't know these members of your Multidiscipline Treatment Team ask to speak to them before operation.
With love
Joy K