Does mass equal to moles times molar mass take into account coefficients?
What do you mean by $\pu{3 moles}$ of $\ce{ 2NaN3}$? The coefficient (the 2) is the number of moles of that molecule that you have. 

If you're looking at an equation with $\ce{ 2NaN3}$ written in it, and you want that 3 times, then you're going to have $\pu{6 moles}$ of $\ce{NaN3}$, so $\text{mass}~= ~6 \cdot 65$ .