So Caato is a good mother after all... poor Caato...
And I think people are missing the point: She did that to protect Jobin and his ability. She wanted Jobin to have 0 blame for what happened to the boy, thats why she didn't called an ambulance, and choose to handle the body herself(so just her DNA is on it) and burry it alive. She wanted that, no matter what happens or if the body is even found, that she takes the FULL blame for it.
And why she burried the boy alive instead killing him first? Equivalent Exchange. She removed Jobin's Rock Disease from him doing that.
As for if what she did was right or wrong, it's of course it was wrong, but that aren't the point: the point is that she sacrificed herself for Jobin's sake. That's why Jobin appears to be very loyal to her.
Edit: This also makes Joshu looks even worse in retrospect, for what he did with her...