Given an arbitrary non-deterministic finite automaton (NFA) with $N$ states, the maximum number of states in an equivalent minimized DFA at least
ans is (B) $2^N$.
In DFA any subset of the $N$ states (for $N$ element set $2^N$ subsets possible) can become a new state and they can remain even when the DFA is minimized. So, maximum we can get $2^N$ states for the minimized DFA. (at least in question must be a typo for at most).
Answer is B. i.e., 2N