I presume by "National socialists," you mean the Nazis. They weren't particular advocates of the free market, but they weren't socialist in a meaningful economic sense. The Nazis did consider Communists as enemies. Their argument that Communism was an extension of Jewishness would be farcical if it weren't so tragic.

But for their part, the Communists would have been perfectly happy to make peace with the Fascists. They (correctly) recognized liberal democracy as a common enemy to their authoritarian dictatorships. Stalin didn't ally with western democracies until Hitler's surprise attack.