The sum of the zeroes \( \alpha + \beta \) of the quadratic polynomial \( p(x) = x^2 - 3x - 4 \) is given by \( \alpha + \beta = -\frac{b}{a} \), where \( a = 1 \) and \( b = -3 \).
Thus:
\[
\alpha + \beta = -\frac{-3}{1} = 3.
\]
Now, we calculate \( \frac{4}{3}(\alpha + \beta) \):
\[
\frac{4}{3} \times 3 = 4.
\]
Thus, the correct answer is \( \boxed{4} \).