For which of the following scenarios will the heavier of two...

The de Broglie wavelength of a particle is given by $\lambda = \dfrac{h}{p} = \dfrac{h}{mv} = \dfrac{h}{\sqrt{2mK}}$.

For particles with the same linear momentum $p$, the wavelength $\lambda$ is the same regardless of their masses.

For particles with the same kinetic energy $K$, $\lambda \propto \dfrac{1}{\sqrt{m}}$. Since the heavier particle has a larger mass $m$, it will have a shorter de Broglie wavelength.

For particles dropped through the same height $H$, their final speeds are equal, given by $v = \sqrt{2gH}$.

For particles traveling with the same speed $v$, $\lambda \propto \dfrac{1}{m}$. The heavier particle has a larger mass $m$, hence it will have a shorter de Broglie wavelength.