Moussa has missed the past three matches through suspension after the midfielder saw red in last month’s defeat to Bristol Rovers for violent conduct.
The 20-year-old served the last game of his ban in Saturday’s 2-0 defeat to Leeds, where Tilson was only able to field a squad of 16.
Alan McCormack was expected to feature at Elland Road despite suffering a foot problem and he could be in line to return against the Bees.
Fellow midfielder Damien Scannell (foot) remains doubtful, meanwhile Scott Spencer is sidelined for the remainder of the season with ligament and tendon damage.
United desperately need to win just their second match in 20 to retain hope of escaping relegation from League One.