If you want the values of both nodes to be on your payload, you need to put the nodes in series and not branching them off separately from your trigger. What’s happening now is the two nodes are executing in parallel, and whichever one is finished first reaches the Webhook Reply Node, and that is the data that is available in the reply. The other goes nowhere since the reply to the webhook request has already been sent.
So build your workflow as one straight path: Webhook -> extract hum… -> Data: Gauge… -> Webhook Reply -> Debug.
And make sure you put the results of both gauge queries at different payload paths or the second one will simply overwrite the first.
Finally, make sure to adjust your Webhook Reply Node to reflect the new payload paths you set in the nodes that came before it.