Evaluate the inner function g(x) at x = -1.

The function $g(x)$ is given by $g(x) = 3x - 1$.
Substitute $x = -1$ into $g(x)$:

$$g(-1) = 3(-1) - 1$$ $$g(-1) = -3 - 1$$ $$g(-1) = -4$$

The function $f(x)$ is given by $f(x) = x^2 + 2$.
Substitute $x = -4$ into $f(x)$:

$$f(-4) = (-4)^2 + 2$$ $$f(-4) = 16 + 2$$ $$f(-4) = 18$$

The value of $fg(-1)$ is 18.

The correct option is B.

$$\boxed{\text{B}}$$