The hybridization of carbon atoms in $\mathrm{C}-\mathrm{C}$ single bond in  $\mathrm{HC}\equiv \mathrm{C}-\mathrm{CH}={\mathrm{CH}}_2$ is 

The bond $\mathrm{C}-\mathrm{C}$ involves $\mathrm{sp}\text{ and }{\mathrm{sp}}^3$ carbon atoms. The hybridisation of carbon atoms in C−C single bond of $\mathrm{HC}\equiv \mathrm{C}-\mathrm{CH}={\mathrm{CH}}_2$ is $\mathrm{sp}-{\mathrm{sp}}^2$ One C atom is bonded to another C atom by a triple bond and is sp hybridised. Other C atom is attached to another C by a double bond and is ${\mathrm{sp}}^2$ hybridised.