Just a thought - could Sucs. be an abbreviation for sucursal, which means subsidiary. so you would have "El Comita" ("The Comet"), subsidiary of Trujillo & Subiña S. in C.

en = in, not and (y = and)
C could be "partner" (compañero)
I agree S is probably not sons, which is hijos.

I also agree the abbreviations should be commonly understood, like "Inc." I'll be a native Spanish speaker from Puerto Rico would have it right away.