The gun bit threw me too. The bad guy is holding something as he gets out of the car to capture Rui and Midori, and you hear a click that could be the sound of a pistol being cocked. But even though I remembered this, I still got briefly confused later because you don’t see any reason why Ran and Rin let themselves be tied up. (The bad guy does have one hand out of sight, though.)

But this bit still completely throws me, even after rewatching several portions of 13 and 14: Why on earth did the bad guys’ plan require an elaborate long-term plan to kill the granddaughter?
1) The only money we hear about is from the theft mentioned twice near the beginning of ep 13.
2) They’re not after the family’s money - it was pretty much lost during land reform (also ep 13).
3) Besides, they apparently intend to leave the grandmother alive anyway. Otherwise there’s no reason to convince her that her granddaughter died from the curse.
4) Sure, they’re “hiding it there,” but why can’t they just leave with it?