Nope. Kang uses Crunch, Mummy activates, but Crunch is still gonna hit twice for the first attack.
252+ Atk Parental Bond Mega Kangaskhan Crunch vs. 252 HP / 252+ Def Cofagrigus: 156-186 (48.7 - 58.1%) -- 52% chance to 2HKO after Leftovers recovery
After that, it does this:
252+ Atk Mega...