Specifically catalyzes the AdoMet-dependent 2'-O-ribose methylation of cytidine at position 56 in tRNAs. cytidine(56) in tRNA + S-adenosyl-L-methionine = 2'-O-methylcytidine(56) in tRNA + H(+) + S-adenosyl-L-homocysteine Homodimer. Belongs to the aTrm56 family.