My Mom (93) suddenly turns on me with regard to who visits us when they have gone. Any advice?

Our grandchildren pop in and out, we look after them once a week. My Mother doesnt get up until 11approx 12.00. So they are only around her for about three hours. Sometimes she is ok . but then we get its to much, they like me best, shes old and shouldnt have to have anyone in the house. To much etc.1 hr later its all me. This applys to family and friend, I also shouldnt go out anywhere. I do my best for her but the abuse is terrible. She then crys and after a while calls me and says .Dont tell anyone that its her because its all me.