Your mother is having RA (seropositive), Vit A and Vit D deficiency. I presume, she must be taking treatment from a Rheumatologist to control the autoimmune inflammation, if not, please consult one. It has to be controlled with disease modifying anti rheumatic drugs (DMARDs) to avoid the rapid joint damage. Regarding the vit deficiencies, Vit D deficiency occurs due to the lack of sun exposure and Vit A deficiency usually occurs in individuals who are pure vegetarian, although there are other causes as well and has to be ruled out. As far as diet plan is concerned, taking 750-1000 ml of the milk per day and egg consumption can ward off the vit A deficiency, Non vegetarian food is also recommended for this purpose. Consuming Vit D in food supplements and good amount of sun exposure will help in reversing the Vit D deficiency. Calcium at least 1 gm/day is also recommended with vit D.