Excess ITC claimed in GSTR-3B not adjusted in GSTR-9. Now what to do in GSTR-9C?

By mistake, Excess ITC was taken in GSTR-3B in the year 2017-18 as compared to the books of accounts. It was not corrected in any subsequent years. Erroneously, in GSTR-9 of 2017-18 also, it was not corrected and the increased amount of ITC was shown in GSTR-9. Now while conducting the GST Audit, how to deal with this issue in GSTR-9C?