Your question is based on a wrong premise. National Socialism isn't a mixture of Nationalism and Socialism.

Speaking very broadly, Socialism has as its goal the ownership of the means of production by the workers, and focuses on class and the relations between classes as the way of looking at a society.

National Socialism doesn't share that goal and neither that perspective. It has Socialism in its name in the same way the Democratic People's Republic of Korea has Democracy in its name.