And then, of course, there is the inevitable mother's feeling of guilt for ignoring the danger signals.
A sense that something was wrong (which a mother might surely feel) doesn't mean such sense was correct. There was danger, obviously. But Beth's sense of what that danger was might have been wrong.
Odd's are greatest that Nat was too old to qualify for the human traffic thing. Most likely, she OD'd from something she was given (prob by Jurine)...interaction with current medication or just a plain OD from a date rape drug or X.
Whether the issue is X or Rohypnol or GHP...it is ultimately a matter of motive on the part of the person with her (and why would Jurine walk away after investing so much in Nat).
If Jurine is a predator (and everything points to that), no one is going to interfere with that process. He wouldn't allow it.
Not to be too intuitive, but his face tells the story.