This is a flag attributed by the source to the government of the state of Espírito Santo, though hasn't got the slightest resemblance to the state flag. It's a green flag with a national-flag-like lozenge in the center, in white, bearing two interwined letters, T and C, in black. This might be related to the state motto
As for the initials T-C, I could generate a number of guesses (Transportes Capixabas, for example, capixaba being the adjective for something having to do with Espírito Santo), but without evidence they are just guesses.
I note from Lloyd's Register 1953 that the Government of the State of Espírito Santo is shown as owners of the Itacoya of 180 tons built 1929 so I guess there is nothing wrong with their having their own house flag. Presumably having a company to run it was not considered necessary although having complete livery for such a small setup is unusual. The vessel was disposed of by 1958.