Dashboard App will not work on one user on MacOS Mojave but other user works fine

I'd trash these files & restart...

~/Library/Preferences/com.apple.dashboard.plist

~/Library/Containers/com.apple.routined/Data/Library/Preferences/com.apple.routined.plist

~/Library/Preferences/com.apple.spaces.plist

~/Library/Preferences/com.apple.systempreferences.plist

~ tilde indicates  your user library folder

Apple hid the Users' Library folders...

Method 1:

1. From the Finder, select the Go menu at top of the screen, and choose Go to Folder.
2. In the window that opens, enter ~/Library, and click Go.

Are these managed accounts? admin accounts ir what?

Ah yes, likely trash that one also.

Great news, take care my friend! :)