Have trouble to found out who this hallmark belongs to.
I can’t help with the manufacturer, but EPNS is a generic term for ElectroPlated Nickel Silver, which comprises a base metal (nickel silver - which contains no silver at all) with a very thin coating of pure silver. Your item is not therefore silver and the mark is more strictly a trademark rather than a hallmark.
The maker is probably Phoenix Pty Ltd, and it is as the stamp suggests an Australian company from the early-mid twentieth century, closing in the mid 1960s.