Regarding the OP, I see 2 problems: First there's not granting a diplomacy check because what the PLAYERS did took less than a whole minute.
That's like saying that because I can describe my character climbing the 100' cliff in less than 10 seconds, he actually gets up there that fast.
(quite apart from the fact that whoever put that 1-minute rule in there never had to put together a 1-minute speech. Go try it: 1 minute is a LOT of time!)
Now I agree that the players seem to have given up rather quickly, but for me, that would have been reason to prompt them a bit: instead of having the NPC just say NO!, I'd have him say something like NO! Whatever for?! thus handing the ball back to the players. In character, I may not be willing to let armed strangers into my house, but I WOULD want to know why they're asking.
The second issue I see is that while you claim to not wanting to railroad them, that is in fact exactly what you do. They have to do exactly what you expect them to do, or else the adventure fails, and you take issue with it when that happens (as proven by your coming here rather than just discarding the plot and moving on to the next one). If the players don't want to enter the dungeon, then maybe it's time for something else.
Now obviously, as the DM, you put in some hard work to create a scenario, and so you do WANT the players to play the scenario. However, that means you need to make it easy on them to do so. Since getting permission to search the house is required for the scenario to succeed, there should never BE a diplomacy check for them to fail. That's like wanting them to enter a dungeon but at the same time putting a lock on the door they need to pick before they can do so.
If you WANT the obvious way to have the possibility of failure (diplo check, pick lock check), that means you need to prepare alternative entrances, whether as blatantly as the collapsing street, or as subtle as having the wife pass by with a bored look on her face. Never rely on the players to come up with alternatives, as they may not (as you have found). YOU are the DM, and if any action at all is cruicial to the campaign, you need to either make it an auto-succeed, or have multiple alternatives ready for the players to try. There's no need to make it APPEAR easy to the players, but that's the difference between DM knowledge and Player knowledge.
That's like saying that because I can describe my character climbing the 100' cliff in less than 10 seconds, he actually gets up there that fast.
(quite apart from the fact that whoever put that 1-minute rule in there never had to put together a 1-minute speech. Go try it: 1 minute is a LOT of time!)
Now I agree that the players seem to have given up rather quickly, but for me, that would have been reason to prompt them a bit: instead of having the NPC just say NO!, I'd have him say something like NO! Whatever for?! thus handing the ball back to the players. In character, I may not be willing to let armed strangers into my house, but I WOULD want to know why they're asking.
The second issue I see is that while you claim to not wanting to railroad them, that is in fact exactly what you do. They have to do exactly what you expect them to do, or else the adventure fails, and you take issue with it when that happens (as proven by your coming here rather than just discarding the plot and moving on to the next one). If the players don't want to enter the dungeon, then maybe it's time for something else.
Now obviously, as the DM, you put in some hard work to create a scenario, and so you do WANT the players to play the scenario. However, that means you need to make it easy on them to do so. Since getting permission to search the house is required for the scenario to succeed, there should never BE a diplomacy check for them to fail. That's like wanting them to enter a dungeon but at the same time putting a lock on the door they need to pick before they can do so.
If you WANT the obvious way to have the possibility of failure (diplo check, pick lock check), that means you need to prepare alternative entrances, whether as blatantly as the collapsing street, or as subtle as having the wife pass by with a bored look on her face. Never rely on the players to come up with alternatives, as they may not (as you have found). YOU are the DM, and if any action at all is cruicial to the campaign, you need to either make it an auto-succeed, or have multiple alternatives ready for the players to try. There's no need to make it APPEAR easy to the players, but that's the difference between DM knowledge and Player knowledge.