Your mother's situation must be fairly serious for the doctor to suggest rituxan. It has been tested for RA treatment but I believe it is still being tested for lupus and diseases like myositis. There is a new test for myositis (a class of auto immune inflammatory muscle diseases) and many people have reported some success with it.
I believe that like prednisone and the traditional immuno suppressants the dire side effects are rare but they can happen. Many people read these reports and decide to try homeopathic treatments which is a mistake when dealing with such powerful and potentially dangerous diseases.
My suggestion is to get a second opinion. Try to find an experienced rheumatologist, preferably practicing in a University research hospital, and see what he/she has to say about your mother's case. If other meds have not been tried then maybe they should be tried first. Prednisone and IVIG are fast acting but most imminuo suppressants take months to kick in. There is usually some impact within 3 months but it can be even longer for a full effect.
I don't have any experience with RA so I don't have any advice on that. There are other meds like Humira for RA but you really need to get a second opinion.
Sorry you have to face such daunting decisions at such a young age. I have advised many people who are afraid of treatment but they should be more afraid of their disease. Lupus if left untreated can be a horrible disease and it should never be untreated. There are NO homeopathic primary treatments that have been proven effective against an active AI disease. Those treatments are often good as a complement to some other traditional treatment.
Bill