Here is the item:
Until the Weavers arrived home at 5 p.m., the clock ticked,
the refrigerator hummed, and
the dog snoring in the otherwise quiet house.
Well done! When you list grammatical items, you must use parallel structure. Here, the clock ticked and the refrigerator hummed are both short main clauses, but the dog snoring ... is an absolute phrase, thus wrecking the parallelism.
To fix the item, change the dog snoring to the dog snored.