Shakti (Mother Divine) is present in both Dharma and Adharma. Otherwise, Ravana (the demon king of Lanka) would not have had the power to stand up against Lord Rama. He was strong and powerful, which is why he could gather might to stand against Lord Rama.
In the same way, if the demon Mahishasura did not have any power, he would not have been able to face Goddess Durga. Is it not so?
A war always takes place between opponents of equal power and skill. A 50-year old man would not wrestle or fight a five year old child.
When the Samudra Manthan (referring to the event of the churning of Kshirsagar, the great ocean by the demigods and the demons) took place, there were the Devas (demigods) on one side, and the Asuras (demons) on the other side. It is because they were both equal to each other in power that they could churn the ocean using the great serpent Vasuki. If the power of the Asuras had been greater than that of the Devas, then they would have simply pulled the Devas to their side. And if the Devas had been mightier, then the Asuras would have gotten pulled to their side. But that is not so. They are both equal in strength, which is why sometimes the Devas win, and sometimes it is the Asuras win.
Sometimes Dharma triumphs, and sometimes Adharma triumphs. It depends on who wins. When Dharma wins over Adharma, we say that it is Satya Yuga (the Golden Age; the epoch of time characterized by goodness and prevalence of morality).
When Adharma triumphs, we say that it is Kaliyuga (the Dark Age; the epoch of time characterized by immorality and downfall of human values).
Who wins in the end of this conflict is decided by Kaal (time).
When the Sattva (wisdom and righteousness) is more, then surely Dharma wins over Adharma. When there is predominance of Rajoguna (activity and passion) and Tamoguna (negativity and inertia), then Adharma wins in the end.
A conflict implies a battle between two equals. Now, the Para-Shakti (referring to the Mother Divine as the primordial energy that creates and sustains all of creation) transcends this conflict and is much higher than it. What is Para-Shakti? It is One without duality or conflict. All are equal and the same before that divine power.