Monoclonal antibodies, such as ipilimumab, may block cancer growth in different ways by targeting certain cells. Biological therapies, such as TLR9 agonist SD-101, use substances made from living organisms that may stimulate or suppress the immune system in different ways and stop cancer cells from growing. Radiation therapy uses high energy x-rays to kill cancer cells and shrink tumors. Giving ipilimumab in combination with TLR9 agonist SD-101 and radiation therapy may be a better treatment for B-cell lymphoma.