Rey is well acquainted with hope. It's the only thing that's kept her sane throughout the years on Jakku. The hope that she would find a scrap that would lead to a week's worth of portions. Hope that she would survive another day. Hope that her parents would come back for her.
She doesn't have to worry about that anymore though. There's no more Jakku, no more Unkar Plutt, no more wasted time on family that would never return. The latter was the thing that cut any ties of hope that Rey held.
But if there is one thing Rey clings to with a shred of hope, it is that Ben Solo's conflict will resolve, and he will follow her towards the Light. At the end, it is that hope that keeps her going.