If a child is watching a favorite sibling getting scolded for misbehavior, which type of neuron is likely to be activated in an empathic response to this observation

The answer is "Mirror Neuron will be activated".

Mirror Neuron is a neuron primarily found in primates. As the name suggests it fires in both case when the animal/human acts or when the observer detect an action done by another, the neuron "mirrors" that behavior of other subject, like the one observing is the doer of that act