How do you deal with a grannie who thinks she knows everything?

My grandmother just camefrom Zambia to Iceland to visit us. She’s been here for 6 days and I feel like I’m already tired of having her:( When Iam at school she doesn’t eat food, but when I come then she starts asking me what she should eat, I just don’t understand that. Then also when she was cooking beans and rice, she disturbed me when I was sleeping to ask me about the rice. I went and showed her, then when she found out how the rice is in a bag she says its not supposed to be cooked in a plastic bag…I said yes, she said ” no” I said yes and she kept on saying no! I got anoyed and went to sleep.

Sorry it’s really long, any help?