"I meant Sarissa to take Maeve's place," Mab said. "But one does not place all one's hopes with any one place, person, or plan. Like chess, the superior player does not plan to accomplish a single gambit, a particular entrapment. She establishes her pieces so that regardless of what her enemy does, she has forces ready to respond, to adapt, and to destroy. Molly was made ready as a contingency."
Near the end of BG Harry meets the third walker, He Who Walks Besides. The Walker also refers to itself as Nemesis. I don't want to get into whether HWWBs is Nemesis or the three Walkers are all aspects of Nemesis. That's something for future books to sort out. No, I'm interested in who is going to confront Nemesis. From our perspective, because Harry is Starborn and has the ability to wield power over the Outsiders; according to Lash, and may be immune to being taken over by Outsiders; if Ebenezer is correct, he seems like Mab's primary choice to deal with Nemesis.
We don't know what the White Council wanted Starborn Harry for. Maybe it's the Outsiders, but it could be something else entirely. It's possible there are multiple roles a Starborn mortal can fill. However, the Big Boss of the entire series appears to be Nemesis. But all you have to do is read the statement I highlighted above to know that Mab has a contingency plan, or maybe it's contingency plans, for dealing with Nemesis and the Outsider threat.
I should also add that Harry is the primary Outsider solution, from our prospective. It's possible that Harry is Mab's contingency plan, but that doesn't matter. For ease of understanding, I'm going to stick with with the idea that Harry is primary. So, who is the backup or who is Mab's contingency plan?
The only other Starborn characters we know who are walking around are Elaine, Listen and Drakul. Somehow, I'm not seeing Drakul as the savior of the human race. In fact, in his final conversation with Lash, Harry makes an intuitive guess that there's relationship between the Outsiders and the Black Court. Then again, maybe the Outsiders taking over our reality would destroy Drakul's food supply so the creature might have a reason to oppose the Outsiders. Somehow I doubt that. If Listen is still alive, which seems doubtful after Harry buried him under a wall of dirt, he might be a candidate, but I'm just not feeling it. If Elaine had appeared in more than two books, I think she could have been an alternative to Harry, but she seems like a character who has been pushed so far to the sidelines as to be irrelevant. I'm sure that Jim will drag her back into the limelight at some point, and we still have to find out if she is Kumori and, or she was responsible for infecting Aurora, but as the being who will defeat Nemesis; well, there's nothing there to indicate she has the ability to do so.
Many of us suspect Nicodemus Archleone has his own plan to defeat the Outsiders. (I don't think it's been explicitly stated that that is the case.) In a scene on top of Marcone's castle discussing who can defeat Ethniu, Mab opines that Nicodemus could cut through her defenses. Mab clearly doesn't have a problem using monsters to get the job done. Of course, Nic's plan is likely to be some kind of scorched earth strategy, but Jim has stated that Mab will sacrifice everything, including herself, to accomplish her goals. If Nicodemus plan looks doable to Mab, she is that rare being who can put expected results ahead of personal issues, and she could always defer killing Nicodemus to a later time.
Finally, a new contender is John Marcone. Mab might see Marcone / Namshiel as a viable choice. If Nicodemus has a plan to defeat Nemesis, Thorned Namshiel might already be all in on that plan. Whether Marcone will agree with such a plan is questionable. Marcone might balk at burning down his own empire to stop Nemesis. However, we don't how long Marcone can remain himself. Like Harry, Marcone is a very willful mortal, but breaking down mortals is what Namshiel and the other Denarians do and have done for millennia.
Whether Harry is Mab's primary Nemesis solution or he is her contingency plan, who do you think is Mab's other choice or choices?
