Answer:
I assume both inner and outer bearings were replaced.
The problem is two-fold; first, the the new bearing cone (cup) may not have fully seated; second, the retaining nut may have loosened.
Get the car up on jack stands, release the parki\ggn brake and pop the bearing nut access cap. Next tighten the nut while rotating the road wheel until the wheel no longer turns. Back the nut off until the wheel spins freely. Grad the wheel top and bottom and push in and out until a small amount of play is felt.
Using a centre or drift punch, deform the raised shoulder on the bearing nut so that the metal forms a U shap in the square alignment notch of the stub axle.
Replace the bearing dust cap and road test the car.
Good Luck
Malcolm