This story line caters to that possibility (yeah I know its very unlikely. I don't buy this either):
The owner of the house (a priest and his son or friend) drove off in their black car (cross etched in the rear window) to get supplies or has another safe house.
This person let their dog out for a walk before going out on their run. When the dog was done with its business it went back to the house and ran off the first time when it saw Daryl.
The second time the dog went to the house coincided with the arrival of the zombies that heard Beth singing and playing the piano an hour or so before.
Daryl opens the door and the zombies charge in and the car shows up with Beth limping towards it. The owner sees what's going on and his/her buddy grabs Beth and throws her in the car.
I think the crux of multiple plot point possibilities lies with that one eyed dog and what actually drew walkers to the residence.
Does the dog belong with the residence; car; both or neither?
What drew the walkers?
Does the car go with the person at the residence or is it separate?
What was the intention of taking Beth?
Your explanation Robin appears to be the most plausible.
Then the question was did they do this with walkers they drew with the dog or with ones that showed up due to Beth's singing and piano playing earlier that day
and the dog was just used to draw them to the door?
There's other possibilities:
1. *The dog belonged to the car owner and both have nothing to do with the house*
Although how likely is it for someone to train a dog to help do drive by kidknappings?
2. *The dog belongs to the residence and the car doesn't*
I like this because it's the most terrifying. This implies someone who lived at the residence either recently left the house to go on a supply run or was overtaken by someone leaving the dog on it's own.
The walkers show up due to Beth's singing and piano playing and the car occupants were just coincidentally driving along and saw Beth and grabbed her when they saw her.
3. *The stray dog and the owner of the house and car are all separate*
It's equally possible the dog is a stray that came to the door for food a couple of times.
The house owner is gone for good or out getting supplies.
The car just happened to be there at the time the house was overrun and took Beth because she was an easy target with her limp.
Any of these scenarios I think has Daryl going back to the funeral home to pickup Beth's trail.