Sending huge hugs and love your way, hug your babies tighter and everynight tell them a nanna story, keep her memory within them alive.
Make a special nanna photo album with as many pics as you can find ( ask family for more) to help you with your stories and for her grandsons to see.
Grief has many sides, hurt, anger, frustration, emotion and more so let these feelings come, don't fight them and cry when you need to, don't hold it all in.
And please make sure you ask for help, losing a loved one especially after only 4 days of knowing that an illness is terminal is going to be hard, no one had time to process that information so sweetness remember we are here to help, especially the lovely geeks who have gone through similar.
((((Hugs))))