Dear Sallu,
From your own statement you had been in the service of Company-A from 23-02-2016 to 19-07-2017 as your date of relief is 19-07-2017. Then how is that you joined Company-B on 23-06-2017? If the termination of your employment under Company-A is resignation, you would have been paid up to the date of relief i.e., 19-07-2017 as observed by Mr.KK!HR. If not so, 19-07-2017 might be the date of orders only declaring the cessation of your employment with Company-A for whatever reasons other than formal resignation. If no typographical error in your post, your joining company-B on 23-06-2017 would certainly indicate that you just walked out of company-A after submitting your resignation or being unauthorisedly absent and joined company-B by suppressing the fact of your employment with company-A. Intentionally there is no mention in the post about the date of your joining in Company-C. It leads to an educated guess that you inadvertently mentioned about your interim employment with company-B and this raised the query. In the absence of a frank disclosure by you, I think no one can help you.