The correctly punctuated absolute phrase is A. , her house bedecked in garlands of flowers,
Absolute phrases modify a noun or noun phrase, but they are not connected to it by a conjunction. They are simply connected by a comma. Furthermore, they can be removed from the sentence without changing its grammaticality or meaning.
Consider:
<em>Señora Alvarez</em><u><em>, her house bedecked in garlands of flowers, </em></u><em>waited excitedly for her guests to arrive.</em>
<em>Señora Alvarez waited excitedly for her guests to arrive.</em>
The meaning in both sentences is the same. A woman is waiting for her guests.
