Sorry to hear the sad news.Thinking about you and your family. Enjoy your precious time together. And know that when the time comes she will be free from suffering. Sending you lots of hugs and positive thoughts for the future. Take care.
So very sad, but for the sake of 'a little more time', would the stress of radiotherapy be worth it? Your Nan evidently thinks not - a brave and wise choice. She sounds like a wonderful lady, and I can understand she must be very precious to you.
I must agree with everyone here, Nan has made the right choice, enjoy this precious time together as best you can, may her journey be a serene one, lots of love. ♥