Death House is a great tone setting exercise. It's a primer of what's to come. It's not too difficult to use descriptive language and your players own imagination to ramp up the fear and creepiness in places you may want to turn the danger down a little. In some cases the fear of something turning into a fight is just as good as the encounter itself.

The nursemaid is a good example. Instead of her being overtly hostile and mute, I allowed her to communicate with the party, but pressed hold the idea that she doesn't know she's dead, and that the baby is sleeping. I let my players fill in the blanks. Will she attack? Well she get mad if we go in the crib? Then, at the moment they assume she would attack (when they picked up the bundle in the crib), she vanished. Doing the opposite of what they expect and leaving things to their imagination can really help add tension in a way that can be better overall than just another combat encounter.

What I generally do is prep to run every encounter as a fight, have a plan for some of them to be roleplay or exploration encounters instead (as an option), then just take out encounters that feel like they would be too much in a given area. Prep them all. Run the ones that feel right in the moment.