As far as I understand, solution A is what Russia uses itself - e.g. Putin and his 'HQ' does not handle any electronic documents whatsoever, all document processing of that level is done with typewriters, not even offline computers; communication is done by wired 'dumb' phones that only do voice and in some cases hardware encryption of the voice.

You can have a hack-proof office by ensuring that no digital devices are present, no computers, no cellphones. You can't hack Putin's emails because there aren't any. There are drawbacks, of course, but it's certainly possible to work that way.