I have heard of only Omar Marmoush as a transfer rumour and he is expected to join them soon. Other than him I don't think Guardiola will make many big signings this month.
Apart from Omar Marmoush, City have also agreed deals for Victor Reis and Abdukodir Khusanov with their respective squads. The reinforcements are very necessary for City, though i think it is Omar Marmoush that will immediately be integrated into the team.
Manchester City are 22nd in the CL league phase table, it is already impossible for them to finish in the top 8, but they must win their two remaining games to remain in the play-off places and stand a chance to quality for the RO16.