Hello,

1. "snap to nodes" is activated

2. I click on an end node of path A and snap it with the other end node of path B

3. I combine path A with path B "ctrl + K"

4. When I join the two snapped nodes, inkcape creates a tiny segment in between.
But all I want is a single node.

After step 3, select the two nodes you wanted to join and with and click the join node button on the tool control bar.

Thank you! Of cours it works.
I should have known this myself. Somehow I kept clicking the wrong button.