Can a dfa return only the final state?
I think there's a misconception.  DFA by themselves don't return anything.  A DFA is a mathematical model.  You can interpret the current state of the DFA when it hits an accept state as containing a result, but that's an interpretation you are making that's not part of the mathematical notion of a DFA.  Alternatively, you can consider a Moore machine or Mealy machine, which are mathematical models that do produce output; you can think of them as like a DFA but with an extension to allow them to produce output.