Step 1: Natural Logarithm Application.
Given the equation:
\[e^{x^2y} = c\]
Applying the natural logarithm to both sides yields:
\[x^2y = \ln c\]
Implicitly differentiating both sides with respect to \( x \):
\[2x y + x^2 \frac{dy}{dx} = 0\]
Solving for \( \frac{dy}{dx} \):
\[\frac{dy}{dx} = \frac{-2y}{x}\]
Final Result:
The derivative is \( \frac{-2y}{x} \), aligning with option \( \mathbf{(B)} \).