Recall the valence electron configuration of carbon:
a) The hybridization of one and one forms two orbitals which leaves two unhybridized orbitals, all half-filled. Thus when forming bonds, the two orbitals are involved in forming -bonds and the orbital would form a -bond. This is why we normally associated sp hybrid orbitals with triple bonds.
b) Try using similar reasoning as above. One and two orbitals form 3 hybrid orbitals which leave 1 unhybridized p orbital. The unhybridized p orbital would form a -bond with another half-filled p orbital and a -bond when looking at the orbital. Thus, we normally associate double bonds with hybrid orbitals.