This video demonstrates the process for installing Windows Updates to an entire network of computers when that network is completely segregated with no internet access and no WSUS access.
Note, there are multiple ways to utilize ‘offline mode’ and this video demonstrates only one method. All methods are described in more detail, with tutorials, here: Cached Mode and Offline Updates
Using ‘Offline Mode’ to Install Windows Updates on Computers That Do Not Have Internet Access or WSUS Access:
The written tutorial for this process is available here: Using Batchpatch In Offline Mode to Deploy Windows Updates to Computers that Do Not Have Internet Access