"Are egalitarianism and feminism opposing ideas or complimentary?"
In theory, they are still different. Egalitarianism is defined as is a trend of thought that favours equality for all people. Feminism as we know is defined as the advocacy of women's rights on the grounds of political, social, and economic equality to men.
In practice they are polar opposites. Here's why.
The feminist definition is derived from the nearly 100 year old FIRST WAVE FEMINIST movement that existed during the times where women did not have legal equality to men like they do today in the first world.
Today's THIRD WAVE FEMINISM that exists in our post-equal Rights first world is going beyond the originally stated goals of legal equality, and is attempting to make women completely equal to men in status and biological advantages. It's no different than trying to make short people equal in all societal outcomes to tall people ... or like making subjectively plain looking people equal to pretty people.
We would never be so naive to believe we can achieve that, and thus, we don't do that. But modern feminism, still deceptively speaking in terms of yesteryears "oppression", seems to be gaining ground by redefining equality completely away from it's original, already achieved intent.
Of course none of this is equality. None of this resembles egalitarianism.