Is there a way to hide my NPCs from the players?

I have a player who's too curious and keeps poking around at the NPCs I've made. I've told her to stay out of it several times, but, as is usual in D&D, the players are ungovernable. I know a lot of people have suggested making monster blocks for them instead, but most of them are plot relevant. For the time I've removed the NPCs from the campaign. If there's a way to do this without having to remove them from the campaign and add them back in every time I need to put them in a new map?

You can quite easily look at the characters you have created without them being in any campaign.

If you mean DDB character sheets for your NPC's, There is an option on the character sheets. Under the Manage button > Character Settings > Character Privacy and turn it to Private, at which point only you have access.

A much more effective solution though is to take those entirely offline and put them in word documents or something, and roll dice manually and add any relevant modifiers.

Changing the NPC sheet to Private just means it can't be opened, unfortunately players in the campaign can still see the details card for them (which reveals their level, class, race, etc.). I have had to create a separate campaign just for my NPCs to keep them from being seen. Unfortunatley that means you can't draw them in to the Encounter tool - but the other option of homebrewing a stat-block (monster) version of them is too much of a pain, especially as they get higher level. You need an entire character sheet, not just a stat-block of a few abilities.

Quote from HarmAssassin >>

Changing the NPC sheet to Private just means it can't be opened, unfortunately players in the campaign can still see the details card for them (which reveals their level, class, race, etc.). I have had to create a separate campaign just for my NPCs to keep them from being seen. Unfortunatley that means you can't draw them in to the Encounter tool - but the other option of homebrewing a stat-block (monster) version of them is too much of a pain, especially as they get higher level. You need an entire character sheet, not just a stat-block of a few abilities.

 

Exactly!  this is the issue I'm having as well. The workaround I've found that works best is adding them into the campaign, adding them to the map I need them on, and then removing them from the campaign and they'll still be on the map and it all works, but it's tedious having to constantly add and remove them from the game. I'd be better if there was a way to make them invisible to the players. As a DM you have to keep info about npcs private from your characters so it doesn't make sense that the players should be able to see anything about them at all, even if it is privated and they can only see the name/species/whatever, that's still more than they should be seeing. 

Make them monsters, and turn off homebrew or remove it from your collection between sessions, so they can't see it.    Then readd them to the homebrew collection a little before the session starts.   You get all the functionality of a character sheet when they're on the tracker, and it doesn't take up valuable account and campaign slots.  

You already said it in your post: make NPCs using the create a monster homebrew feature. If you're making NPCs using the character builder you are building NPCs incorrectly. They don't follow PC rules.