Splitting from this thread:
A year later (and hopefully somewhat wiser), I watched this again and it's quite obvious the OS is not in Situation. The story's problems are present before Kevin gets stuck home alone: There's family chaos, the Wet Bandits are already active, etc.
Rather, I think MC Kevin is in Situation (the root of it being an overlooked kid, which develops into being home alone).
Based on that I quickly threw together a storyform that looks pretty good, OS in Activity, Doing*, Experience, Determination and MC in Situation, Progress, Fact, Unproven. Dramatica outputted an MC Unique Ability of Security which sounds pretty darn perfect!
* The OS fits Doing better than Obtaining because: a) the Wet Bandits are not concerned with any particular score, just with the burgling itself, b) Kevin's busy with protecting his home and living alone, c) the parents are concerned with parenting. Maybe the Goal of Home Alone is "protecting the family" which includes the family home. Or maybe it's just spending Christmas together!
The Story Goal is a bit tricky. I think it's "protecting the family" which includes protecting the family home and making sure Kevin is okay. But it might just be "spending Christmas as a family".
The IC is definitely Old Man Marley; he's the one with the Change resolve shown in the heartfelt scene in the end (though note like @jhull has mentioned, the moment of the IC's Change is off-screen; we don't see him actually call his son).
However, I believe there is some sharing of IC role between Old Man Marley and Kevin's mom. The big hug at the end definitely felt like an RS resolution moment, as did their fight at the beginning.