Epistaxis or nose bleeding can be caused by several disease conditions. You mentioned that your husband is hypertensive. How is the blood pressure control? If the blood pressure is uncontrolled, there is a possibility that the epistaxis was caused by this. Other conditions that can cause epistaxis include hematologic problem and nasal polyps.
It would be best to have your husband seen by an ENT specialist for further evaluation and management.
If your husband has an enlarged spleen from the lymphoma, his platelet count may be low. This will cause bleeding from nose like u describe. The good news is removing the spleen will correct this problem almost 100% of the time, as well as rid him of the primary site of the cancer. So if your husband has spleen discuss this with his oncologist.