I've never had to deal with MBB (yet), so this is just my two cents worth.

Cut the plants off at the ground, much of the soil nutrient value is released when the roots decay.

Running the plants through the shredder should kill most of the larvae. Composting should kill the remainder, if your compost pile heats up properly & gets turned over. If the plants would just be thrown on top of a cool compost pile, I wouldn't recommend doing so.

Are there a whole bunch of bean plants? If not this may work: I've stuffed infested foliage in several big black plastic garbage bags, tied them up tight, and left in the sun for a few days to 'cook' the offending insect (has worked with white flies). But you're right, you do NOT want active bean beetle larvae to find a way to make it over the winter.