# Does the subset sum problem remain $NP$ complete when we increase word size and restrict number of words?

Is the problem

'Given $m=\big\lceil{n^b}\big\rceil$ with $b\in(0,1)$ integers $a_1,\cdots,a_m$ each with $\lceil\log_2 |a_i|\rceil=\big\lceil n^a\big\rceil$ with $a\in[1,\infty)$ is there a subset that sums to zero?'

$NP$ complete?

The reason I ask is this problem can be solved in $2^{O(n^b)}=2^{o(n)}$ time.

Your problem is not really well-defined, since it's not clear what is the parameter $n$. That said, under any reasonable interpretation, your problem is still NP-complete, as can be shown by padding. Given an instance of subset sum, we can create an instance of your restricted subset sum by adding a lot of zeroes to the set.
Subset sum is solvable in polynomial time if the weights are polynomially bounded. More generally, if there are $m$ integers and each one is bounded in magnitude by $B$, then subset sum can be solved in $O(mB)$. In your case the weights are not polynomially bounded.