Yes, but they were apparently aware she was leaving the home and being taken advantage of by strange men. She could have just as easily ended up contracting aids as she did getting pregnant.
Again, I'm not saying they are guilty of anything. For all I know they were in constant contact and filed many complaints with the home. However the state should look into both the home and the parents. It could be a case of no wrongdoing, and this woman simply slipping through the cracks, or not.
It's the assumption that they "did nothing" that's the problem here. Nowhere has that been stated, or even implied.
I'm curious to know what you would consider "doing something". Obviously, the woman is difficult to care for, necessitating a care home in the first place. The law prohibits restraint beyond a certain extent. And the thing you are perhaps not considering fully is that, whatever her mental capacity, she's 34 years old.
Any parent in the world can tell you that child with a 6-year-old's mental
and physical capacity is a sneaky, ingenious little creature who can rival Harry Houdini's escape artist abilities. I can't even imagine with a person with a 6-year-old's mental capacity
and a 34-year-old's physical capacity would be like to try to keep out of trouble.