Is two arrows on each state necessary in DFA?
You are correct.

In an NFA, there might be more arrows (for epsilon transitions, or multiple transitions on the same symbol) or fewer arrows (for undefined transitions) than there are symbols in the alphabet. In a DFA, neither of these is allowed: in fact, a DFA is specifically defined as an NFA where neither of these things happens.

Therefore a DFA will always have exactly as many arrows from each state as there are symbols in the alphabet.