Forgot grandson in the car

My mom picked up my 3 nephews (ages 11, 8, and 5) so that they could have a sleepover. By the time they arrived to the house the 5 year old was fast asleep. She parked in the garage, unloaded their things and the kids went inside. About 30 or 40 mins later mom hears someone honking their car like crazy and she finds that it was the 5 year old who was forgotten in the car and woke up. He was terrified and crying and my mom blamed the 11 year old because he didn't look after his brother when he got out of the car. I'm so livid at my mom because she never accepted responsibility. Then got really mad at the 11 year old for notifying his mom of what happened. I personally take that very seriously because that's how many children have lost their lives. I'm so thankful that he woke up and alerted her.

As soon as I heard of this I felt physically sick because it's that easy for a tragedy to occur 😞 That is why she'll never watch my 2 year old daughter and I dont care if I'm overreacting. I don't feel comfortable especially since she won't let my daughter tell me if something goes wrong in her care which I would have every right to know.