Lupus is a disease involving the connective tissue of the body. It sometimes affects the lymphatic system as well. Lupus does not cause lymphatic cancer. Your aunt is unlikely to develop lymphatic cancer as a result of having lupus.
Lupus and Lymphoma are not specifically linked. However, people who get cancer of the lymph nodes often suffer from some sort of autoimmune disease, such as lupus, rheumatoid arthritis, or epstein-bar virus. Having lupus does not guarantee a lymphoma developing though.