If I have a temporary sprite on my bf and a hidden unit, then it comes my turn and sprite dies, what happens to my hidden unit? Do I score hold points?

Yes, you can score the Hold point — but only if you react to the Temporary trigger by playing your hidden unit.

Here's the sequence:

1. Your Beginning Phase starts. The Sprite's Temporary keyword triggers ("kill this at start of controller's Beginning Phase") and goes on the Chain as a pending item.
2. Because a chain is open, you have a Reaction window. Your hidden unit gained Reaction from being Hidden, so you may play it now from facedown for [0].
3. If you play it: the hidden unit resolves first (LIFO — last in, first out), enters the battlefield, then the Temporary trigger resolves and kills the Sprite. You never lose control of the battlefield and score the Hold point in the Scoring Step. (FAQ #6560)
4. If you don't react: the Sprite dies, you now have no units on that battlefield, you lose control immediately, and your hidden card goes to the trash (FAQ #4628 — hidden cards are discarded when you lose control of the battlefield). You do not score the Hold point.

Key point: The hidden unit doesn't save itself automatically — you must actively play it as a Reaction to the Temporary trigger. If you pass priority without playing it, both the Sprite and your hidden card are gone.