The answer is no. Hubble's visible-light resolution is about 0.05 arcseconds, which translates to 90 metres per pixel, far too large to make out anything that's "merely" bus sized. An imager would need to in orbit around the moon to have any reasonable chance.

It seems like they're hoping to detect the plume of dust caused by the collision, however.

The crater created by the impact with the dust throw around it will be bigger.

...but there's a imager in orbit around the moon, Lunar Reconnaissance Orbiter.