She's getting off very light here.
She'll be a free woman in a few years.
Not enough in my opinion.
The mom said that they called the family into the office in the middle of the night to mention the plea deal. Only gave them a few hours to accept/deny it. Personally, I would have said no or make her admitting guilt and explaining what happened part of the condition of the deal. You can tell that the mother regretted accepting the deal as her opinion about it changed right after.
Their only true chance of getting the full story in what happened is if Billy Ray Turner confesses and tells of what happened. He's the one who should have gotten the plea deal instead if we're being honest. Now she has no incentive to talk and he doesn't either since it won't matter anyways.