From what I have read the rubble asteroids are the hardest to do something about. We can redirect a lump of iron provided we have enough warning, but rubble asteroids are much trickier since you cant just push them out of the way. The only two options are gravity tractor or demolition. Neither option is easy and both require lots more advanced warning compared to a similar mass solid asteroid.

Bunker busters wouldnt be particularly useful since the warhead wouldnt survive the impact at the speeds necessary to get sufficient penetration on a rubble asteroid big enough to need redirection. The drone idea is harder, but if you can get several deep enough with big enough bombs the blast should at least nudge the thing off course.

Yeah, it would have to be very close. The energy dissipates exponentially with distance. The more surface area exposed to the blast the asteroid has the more energy would be transferred though, so for really big ones it might be more effective than the basic chemical thrusters we have now. Not saying alot of course. A dinosaur killer has enough mass its debatable if we currently have the tech to deflect one that would hit within a decade or two.

Close nuclear detonations would still push the asteroid simply by differential heating and vaporizing the rock on the facing side. Not much of a push, but it is one. Nukes might be the only recourse for rubble asteroids too. You'd have to have the warhead on a robot that would push itself inside before detonating for it to do any good, but I can't think of a better option.

Well we have to get it all up there first and we dont have teleporters.

Sure. Until they get caught in the Kessler belt we are busy building.

Given our track record with junk in orbit it could be a positively glowing future here in a century as it all falls back down.