So my niece hasn't been in school all week. My brother went monday to see about getting her in…

So my niece hasn't been in school all week. My brother went monday to see about getting her in school here but yet they need everything. Social, birth certificate, shot records etc and he has none of it. He contacted her mother which said she would look for the things and send him. She finally contacted him again and told him 2 days ago she couldn't find anything and would come get her saturday. Which is today and no sign of her. Like wtf do we do??? She needs to be in school and her mother seems not to care at all. And it's not my sisters place to drive them all the way back to GA to take her home when she took her home last weekend and she couldnt find her mom cause she was mia for a week so she came back up here to stay with her dad. Like this makes no sense.