Contact - TUBE FLARING TUBE FLARE ORFS FLARE 37 FLARE 45 FLARE

The song that Dean is humming to calm himself down on the plane is called "Some Kind of Monster" by Metallica.

After being killed by a hellhound in the 12th season of Supernatural,  Eileen returned to the 15th and final season first as a ghost who was able to escape hell when Chuck/God (Rob Benedict) opened the rupture.