Scared to go downstairs?

Today my mum received my report card with all my grades in it and i pretty much got B's in most my subjects. She got really pissed off and started screaming at me for not getting A's. like WTF! I've been stuck in my room for the whole day and haven't eaten anything. I'm afraid to go downstairs and face her because then she'll start screaming again! What shall i do? I've been on my laptop stuck in my room for 7 hours!!