Mobsync.exe can be found in [systemdrive]:windowssystem32 folder. If the sytem drive is C: then it can be found in C:windowssystem32 folder.
This synchronizing utility can be launched from Run window or from command prompt by executing Mobsync command.
When launched this application would start with the window shown below.
Here we can configure whether or not to sync offline files during log on and log off. We can also enable or disable sync for particular connection types. We can also schedule synchronization at specific times by clicking on the scheduled tab in the above window.
As per my understanding it looks like that Mobsync is involved in the offline files synchronization only during log on, log off and other scheduled times configured in Mobsync setup. When the shares are online, offline files itself takes care of the synchronization and Mobsync is not involved. Mobsync is neither a service nor it runs all the time on the system. It is invoked only during logon and logoff sync or when the user explicitly invokes it by running Mobsync from command prompt or from Run window.