If travelling at same speeds, which of the following matter waves have the shortest wavelength?

Relation between wavelength, mass and velocity:

$\mathrm{\lambda }=\frac{\mathrm{h}}{\mathrm{mv}}$

velocity is same and 'h' is the Planck's constant:

$\mathrm{\lambda }\infty \frac{1}{\mathrm{m}}$

Alpha particles $\left({\mathrm{He}}^{2+}\right)$ has the highest mass, thereby associated with the shortest wavelength.