** Well, you gotta remember, this is Basic D&D, so really, combat is made up of whoever gets initiative, then movement, missiles, spells, and melee. You all are clustered by the door so you could move in single-fileish and on one side of the room (say the north wall) then the fighters could move in behind you and cover the door having stayed near the south side (so they wouldn't get in your way)).
However, you can only do this if you gain initiative on this next round because no one's currently engaged by the monsters at the moment. If the monsters win and close in melee, then you can't move as much.