While technically this is a NES inconsistency bug, it's very simple to fix (just the default item drop). Moldorms are supposed to drop Rupees and I'm not sure what else (possibly hearts and fairies too).
Moldorms don't drop... anything?
I don't think Moldorms ever dropped items in the original NES game at all.
It absolutely does, I just played it on the NES. Kill the Moldorm in Level 2 and see.
I *think* I remember a TAS run where bombs were dropped in LV2. ...It's been a while though so I might be wrong. It's possible they have the weapontype->supplimentkilldroptype ability, or whatever(..something along the lines of wooden sword = no drop, stronger item = drop).
*shrug* I've never heard of that (is that something in ZC?), but I killed it with a wooden sword and got a Rupee.
Eh, I probably just made that up. :P ..But yeah, they definitely drop stuff.
Okay, I did a little examination in a ROM of The Legend of Zelda, and I discovered that Moldorms drop the following items at random when killed: Heart, 1 Rupee, 5 Rupees, Fairy. Those are the same items dropped by a red Octorok, so in conclusion, the Moldorm should use the default item drop set. I'll go ahead and make that adjustment in my current ques project.
PS: Should this also be applied to the L2, L3, and L4 Moldorms that are exclusive to the 4th Quest?
That would be a judgement call on the part of the designer, but I'd say most likely no. However, since the not-dropping of items was based on the original's not-dropping behavior, and that behavior was in fact wrong, then an argument could be made that they should have item drops as well. On the other hand, enemies often have different drop sets among their variants, so it almost seems logical that the different levels would have different item drop sets.
Fixed......
Confirmed fixed.