Two children are dead. Should the grandmother be in prison?

Savannah
I'm watching the Steve Wilkos show and I'm honestly confused. I'm not sure if it's because the show is fake or because these people are crazy. But basically a woman left her son with her mother for a night because she had an ultrasound appointment in the morning and didn't want to wake up the child or make extra stops. While at her appointment, she got a text message saying her toddler son and her two year old sister are dead. The children walked out (the doors were apparently open) and got in the pool and drowned. The grandmother of the boy was asleep until 11 am, she claims. She is a known meth addict. Because the mother of the boy left her son with a drug addict, she lost custody of her other child once they were born. But the grandmother did not go to prison. I'm wondering why the woman was punished when the grandmother wasn't? Admittedly I understand why she lost custody of her child, but why is the grandmother not in prison? Two children died on her watch. But why would she leave her son with her drug addicted mother? It's a sad situation but what do you think?