Hi,
It will be cold at night.
I was actually in Housekeeping in May one year, when there was still snow and the roads were closed, plus it was raining (= leaky eating area)... We took our down throw covers and fleece throws (the kind you wrap in on the couch), and slept so toasty warm. It's been a while since I've been in a Curry Village tent cabin, and from what I remember we had sheets and army blankets - wool blankets (we stayed in June). Do you have any comforters that you could take with you? My brother is going April 10-15 and staying in Housekeeping, and I may join him. I'm planning on taking my comforter with me and a beanie to cover my head at night. You should also take some of those slipper socks, especially for the kids so they can keep their feet warm at night.
Keep in mind that the bathrooms are shared so you should have flashlights handy to walk to them if you need to use them in the middle of the night. At least, the bathrooms do have lights. Let me know if you have any other questions.