Lord, You have watched these grandparents through of their lives, seen their struggles and high points, and watched them worry over what is to come. Show your mercy in their situation, which may seem impossible to them. May their love for each other grow stronger as they face this together. Use these last years/months of their lives to show love, bring family closer together, and build character in everyone around them.
But most of all, relieve them from the distresses that make no sense and are so difficult to handle. Relieve them of pain, both physical and emotional.