Does Shadows Call trigger if you kill the unit Reaction Speed?

Yes, you still draw 2. If the unit targeted by Shadow's Call is killed at reaction speed while the spell is on the chain, the spell still resolves — you just miss the "Give it [Temporary]" part.

Here's why: Shadow's Call has two instructions — "Give it [Temporary]" (which requires the targeted unit) and "Draw 2" (which doesn't target anything). Per Rule 359.3.e.11, instructions that can be partially followed are followed as much as possible. The "Give it [Temporary]" instruction fizzles because the target is gone (Rule 359.3.e.7), but "Draw 2" has no target dependency, so it executes normally.