This phase I/II trial studies the side effects and best dose of bendamustine hydrochloride when given together with gemcitabine hydrochloride and to see how well it works in treating patients with relapsed or refractory Hodgkin lymphoma. Drugs used in chemotherapy, such as gemcitabine hydrochloride and bendamustine hydrochloride, work in different ways to stop the growth of cancer cells, either by killing the cells or by stopping them from dividing. Giving more than one drug, combination chemotherapy, may kill more cancer cells.