(In each case, because we have switched to photons, the energy on the left has to be increased by a factor of 2).
1.
dp.dx. >= h/(4Pi)
dh/lambda . dx >= h/(4Pi) (substituting for the momentum of a photon)
dh.nu/c . dx >= h/(4Pi) (rewriting the wavelength in terms of frequency and light speed)
dE/c . dx >= h/(4Pi)
dE.dx >= hc/(4Pi) (multiplying through by the speed of light)
2.
Using two different variables which define the Uncertainty Principle
dE.dt >= h/(4Pi)
Now, since speed = distance/time; therefore time = distance/speed. Then, for a photon the speed is the speed of light c and the change in distance = dx.
Therefore dE.dx/c >= h/(4Pi) So dE.dx >= hc/(4Pi)
3.
dp.dx >= h/(4Pi)
d(mv).dx >= h/(4Pi) (Since momentum p = mass m x velocity v)
For a photon, the velocity v is the speed of light c and m is the equivalent mass using Einstein's mass energy relation, E/c^2.
Substituting these in the above we are lead to the same result:
dE.dx >= hc/(4Pi)