My grandmother was diagnosed with stage four cancer. I feel helpless.
Oh no, I am so sorry to hear that. That is awful and makes me sad. Have you talked to anyone about it?
I have spoken to our minister about the situation. It's hard to watch her go through this and there isn't much I can do. I can just love and take care of her.
That's what you need to focus on is just giving her all of your love, she will cherish it. I'm so sorry you're going through this, I hope that you can find peace with the situation.
Thank you for the kind words. It gives me hope for the future. 
I am glad, I hope you have a great day today!