Cox has quickly adapted to life as a Football League manager and enjoyed an unbeaten month with 10 points from 12.
The highlight was last weekend’s hard-fought 1-0 victory at fierce rivals Chesterfield which ended the home side’s unbeaten record.
Also nominated are Jim Bentley (Morecambe), Paul Cook (Chesterfield), and Keith Hill (Rochdale).
Marriott has just turned in two superb man of the match displays in a month in which he only conceded two goals and has also enjoyed two successive clean sheets.
Etienne Esajas (Scunthorpe United), Abu Ogogo (Dagenham & Redbridge) and Antoni Sarcevic are the other players nominated.
The winners will be announced on Friday.
The judging panel comprises Sky Sports Football League expert Don Goodman; Football League head of communications John Nagle; League Managers’ Association director Olaf Dixon and Sky Bet head of football Paul Wiggins.