If during a showdown, my Draven Audacious dies from an opponent's spell, does it count as dying in combat?

Yes, if Draven, Audacious dies to a spell during a Showdown while he is still participating in combat, it counts as dying in combat.

Why it counts as dying in combat

A unit is considered to be "in combat" if it currently holds the Attacker or Defender designation. These designations are assigned when a unit enters a contested battlefield and remain until the combat ends (Rule 461.7.a) or until the unit leaves the battlefield (FAQ 835).

Because a Showdown is a window of opportunity that occurs during the combat phase, a unit that is killed by a spell while still present at the battlefield retains its Attacker or Defender designation at the moment of its death. Therefore, the death occurs while the unit is "in combat," triggering Draven's ability: "When I die in combat, choose an opponent. They score 1 point."

Important Distinctions

• Presence is Key: If Draven were moved away from the battlefield (e.g., by a spell that returns him to your base) before he was killed, he would lose his Attacker/Defender designation. In that scenario, he would no longer be "in combat," and his death trigger would not activate.
• Timing of Death: As noted in FAQ 8707, effects that kill a unit during a Showdown (such as delayed triggers or spells) resolve during the combat phase. Since the unit is still at the battlefield and holds its designation at that time, the death is attributed to the combat environment.

In summary, as long as Draven, Audacious has not been moved off the battlefield and still holds his Attacker or Defender designation when the spell resolves and kills him, his death trigger will activate.