ITC not passed on

CA PARUL KHATANA (Self practice at KHATANA & ASSOCIATES)   (118 Points)

14 March 2019  
In gstr 1 for Sept. 2017, B2B sale booked as B2C. consequently such party is failing to avail ITC. Such error has come into notice now only.
is there any way to rectify such error and make the itc available to the buyer?
can it be rectified in annual return, if yes then how?

thanks