Hi Rachana
It looks like you want to use Multi tenancy. Lets say for example you want to only show Tasks linked to an Organization A when all users of Organization A view tasks Overview page . Just create a one to many association between User and Tasks and constrain your Task list like this:
[Task_User/User/User_Organization/Organization/User_Organization/User/id=[%CurrentUser%]]
Similarly you can constrain any data for your Multitenancy supported application