The deacon should check with his bishop to be certain, but my guess is no. If his marriage was annulled and presumed never to have existed, but he is already ordained to the diaconate, then the situation is that of a single, ordained man. In both the Western and Eastern churches, already-ordained men are not allowed to marry.
Even if there were some loophole this deacon could slip through, I would strongly urge him to resist the temptation to find it and exploit it. He entered the permanent diaconate with the expectation that he would live a celibate life should his wife predecease him. That the possibility of lifelong celibacy has caught up to him far sooner than he expected is no reason to seek to deny our Lord such a sacrifice. He might even consider offering up his celibacy in union with Christ’s cross for the salvation of his former wife.
