I don't think you do defend against that. Even if you buried your base, a direct strike by something that big and fast would almost certainly cause you problems unless you were very deep. The crater is 40 meters across and while it isn't as deep, the shockwave anything under it would have felt probably would have been pretty brutal.

A potential Moon base would count on direct strikes by very energetic meteorites being extremely unlikely.

I think reactive armor might be an interesting strategy. But, then again, it was traveling at 40,000 MPH, which, I think, places it at about twice the velocity of high explosive plastique... So, would blasting it, before it blasts you, actually work?

I think there would need to be a complex early detection and warning system, capable of intercepting high speed objects, well beyond what we consider normal terrestrial speeds. Being lazy, I'm tempted to just say "why not some lasers, maybe?" and shrug, but maybe there are some cooler options possible?

Seems like a pretty unexplored deficiency of moon habitation.

I'd expect that it's such a rare and localized event that you probably wouldn't prepare for it.

But, wouldn't less meteorite crashes happen at the poles? Would that be the safest base location?

Make it movable, and a alarm system?

And by movable, not in "left-right" but "up-down". I think is easier to deflect a blast if the base move up, instead of try to run...

Track any asteroids/debris that could impact the moon and keep it out of the way.

I would think the ideal moon base would have multiple layers, the innermost an oxygen volume and the outermost a thick absorbing defensive layer against space debris, enemy/terrorist attacks. Dome structure perhaps.

Alternatively - mobile moon bases, and be super ready to spot space debris.