I am not very familiar with Apple network discovery protocols, but on Windows every computer broadcasts the machine name (and sometimes usernames) to the entire LAN (using MS Windows Browser Protocol, which uses SMB). There could be an equivalent thing that is enabled by default for OS X.
In general, if you have Host-guest network communications and VMTools support disabled, the VM shouldn’t have the ability to access host information. As always, there could be undocumented features, side channels or exploits that would allow an attacker to extract information about the host, so depending on the level of security you need here I suggest doing some research on that.
Nothing beats a separate, physically disconnected machine.