Final answer:
The RN should prioritize providing emotional support and counseling.
Step-by-step explanation:
When prioritizing care for a family grieving the end-stage cancer of a loved one, the registered nurse (RN) should prioritize providing emotional support and counseling. Grief reactions can be intense and varied, so offering a compassionate and understanding presence can help family members cope with their emotions. While financial assistance, regular family meetings, and end-of-life discussions are important, emotional support should be the primary focus to address the family's grief.