Royal Marine Commandos in 1944 were on the same War Establishment as Army Commandos.
Commando Headquarters.
Signal Section
Administration Section.
Five (5) Fighting Troops ( normally A, B, X, Y, and Z Troop ) each with three officers and 65 other ranks.
Heavy Weapon Troop ( S Troop ) consisting of two officers and 40 other ranks armed with two Vickers machine guns and two three inch mortars, although 48 increased these to four of each after June, manning them alternatively as the situatiion required.
[Source: Haste to the Battle, author J.L. Moulton].