Hi Mr.Shetty,
In this case since you are going to decommission the 4.x infrastructure (including the ESXi hosts & VC VM) then I wont go through the pain of taking downtime and upgrading the infrastructure to migrate the VMs. If I were you, then I would use VMware Standalone Converter, that can be downloaded from www.vmware.com/go/download-converter and install this binary on a windows VM, preferably in the same network and which does not have any firewall between the 4.x and 5.x infras. Next I will start doing a V2V conversion where the source would be VMs on 4.x and destination would be ESXi/VC for 5.x. There are many best practices/troubleshooting information that you will find about using Converter.
Let me know if you have any specific questions about this workflow.
All the best.