Hi there Gopinath,
It's an old question, so you might have already found an answer elsewhere. If not, take a look at my article on dynamic column mapping:
Dynamic File Column mapping in SSIS. - SQLServerCentral[
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My solution deals with variable columns in flat files where all rows have the same number of values as there are columns in the file. However, in the Script Component used in my solution, it's easy to implement code changes to handle any differences from row-to-row as the data is being read.
Regards,
Hiske