Grant serves the second instalment of a two-match suspension after picking up 10 bookings so far this season.
Loanee Jean-Yves Mvoto is still sidelined after undergoing a hip operation, while Osei Sankofa is missing with a knee injury.
Johnny Herd also faces four weeks on the sidelines with a hamstring tear he picked up in the win over MK Dons last week, leaving the Shrimpers with a defensive headache.
However, Tilson does have options in attack after completing the loan signing of Jabo Ibehre last Thursday.
Ibehre can operate on the wing or as a centre-forward and will hope to be given a chance to impress against the Canaries.