The correct answer is:
Demetrius is chasing Hermia, and Helena is chasing Demetrius.
Demetrius has been granted approval to marry Hermia. But Hermia is fleeing to the woods with Lysander, who she really loves, to elope together. Demetrius goes to the woods chasing Hermia, who he loves. And Helena is chasing Demetrius, her fiend who she secretly loves.