Can we take "Death Company Tycho" in an army without a Death Company?
Yes.
He is an individual model. He does not come attached to the Death Company nor can he join it, because he is not an Independent Character (the 'normal' version is an Independent Character). This is how the rules are written and was confirmed in the Blood Angels FAQ published on the Games Workshop website, last updated February 2013:

Q: Are the Sanguinor, Mephiston and Death Company Tycho Independent
Characters, or single model units in their own right? (p.41, 47, 51)
A: Single model units in their own right.