Hi and welcomeVinita,
I dont think the updated definition files are the problem as they are incremental. I looked at my own files and I agree the total size is a lot bigger than it should be(86mb)
The Pic below shows files within the Avast Data file which on my system anyway seems too large at 42 mb.
Hopefully someone knows wether the INTEG file(22mb) is a nessesary component or not. The report file is where all your logs from previous scans go and i think can be cleaned out.