Let me just put my two cents on this stabbing in the back.
Beyonce and Jay-Z not showing up is disrespectful. They must've known how this was important to Rih and how much she wants to do this because of her granny.
I can't believe how much stuck up Beyonce is, calling her one time 'family' (A FAMILY!!!!!!) just to leave her hanging like this. When I think about it, she has always been like this. It's fine, but don't you dare calling her a family. 
But Rihanna doesn't need them, I'm sure she realizes what kind of people they are and isn't bothered by those things.
God I'm so glad Rihanna is not like that, her heart is full of love and would help anyone she considers even a tiny bit of a friend. This just proves what kind of people Beyonce and Jay-Z are. (Yes, I know Jay donated money and all that, but showing up, caring and supporting RIH is a totally different thing.)