Portsmouth soared away from danger in April by collecting 13 out of a possible 15 points, with Charlton Athletic loanee Hollands providing a solid base in a new defensive-midfield role and adding three goals.
Bury defender Mills, meanwhile, was a rock at the back for the Latics as they surged into the top half.
Fleetwood Town midfielder Morris scored his first two career goals, both of which were winners, last month as Fleetwood guaranteed a spot in the playoffs.
Lastly, on-loan York City goalkeeper Powell, also from Charlton, has now kept 13 clean sheets in his last 15 games. York conceded just once in five April games.
The winner will be revealed on Friday morning.