Excellent question! In Anthills of the Savannah it is clear that by having two main female characters (Beatrice and Elewa), Achebe is focussing on women to an extent that he has not really done in his other novels. And what women they are! In particular Beatrice is the most rounded character in this novel and Achebe goes to some lengths to present her in mythical terms - representing her as Idemili, the goddess who oversees mortality. It is Beatrice who connects with the culture of her land and who grows in wisdom throughout the novel and defies cultural norms at the end by naming Ikem and Elewa (a responsibility that was strictly male) with a boys name, meaning "May the Path never close".
From Beatrice's name, which means "A woman is also something", we can see that Achebe is clearly trying to make a claim for equality through the character of Beatrice. Beatrice is clearly intelligent and well-educated, having a degree from London. She writes fiction and is also attuned to the common people, represented in the character of Elewa.
So, on the whole, we see Achebe giving a very positive representation of women in this novel. However, to criticise this view, I find it interesting that Ikem only enjoys Beatrice's fiction because of its "masculine qualities". This presents a slightly sour note in the representation of women in this novel. Women should not be appreciated for their ability to imitate male gender qualities. However, on the whole, this is a slight niggle that does not take away from the overall positive impression of women. Key to, for me, is the way that Beatrice has not sought power yet has found herself in a position of some responsibility. She cannot understand why others find her ambitious. The exact oposite of Sam and his attitude to power.