I wanted to convert Caesar-II files from version 7.0(Caesar-II-2014) to age old version 5.2 for client. Is there an easy way to convert these files in a batch(total 100-150 files)? or converting higher version files into neutral files first; is the only prudent option?

There is no utility to convert files to earlier versions. Even using the neutral file method, you will still need to edit the CII files and remove any data from v.7.00 that did not exist in v.5.20.