Barely knows? She grew up in that town, Einar was her FIL that she had a relationship with prior to her husbands death, as well as Mitch that had worked with him on that farm for years.

I think that's wrong if for no other reason than the lines where Einer observes what a nice kid she has what a good job she's done despite everything. Her life has been full of poor choices and guilt since her husband died but this story is the point in her life when she starts to recover control.

I don't think she was an awful mom.
Here's why
She felt overwhelmingly guilty for the death of Griff and felt as if she didn't deserve anything better than being torn down verbally, or beaten. She was in an extremely low place in her life. She was self destructing. Her daughter was definitely a victim of it, but not because her mom didn't love her.
We see as the film progresses she begins to forgive herself. Once she forgives herself she begins to live again.
As for her leaving Griff with 2 men she barely knows
She did know her father in law prior to her husband's death. She also knew Mitch because when she first got to the ranch she calls out to Mitch, by name. Einar was the girl's grandfather. Not saying there aren't creepy grandfathers, but I think she knew he wasn't one. He was just suffering from sever depression from the loss of his son.
As for letting her daughter walk back to the ranch That happened before she knew her ex was in town. It being such a small, small town she figured the girl would be fine.
She definitely didn't get the mother of the year award, but based on what she was going through, she could have been much, much worse.
Personally, I thought it was a beautiful film with outstanding characters!

Agreed. And she also lets her daughter go camping with her grandfather knowing that her crazy ex is back in town and knows where they live.