Everyone seems to headcanon Dib and Gaz's mom, if they even have one, as a scientist like their father. But what if she was a politician instead? The reason we never see her is because the show takes place during a period of time when she's busy in "Presidentland". She's just like Dib in that she's the only sane Congresswoman who sees the blatantly stupid/unethical policies her colleagues are trying to pass and gets no support from her own party when she tries to stand up for what's right because everyone thinks she's too radical for not wanting to compromise and appease the opposing party.
She comes home for one episode because she had to abide by her own principles and abstain from voting on a spending bill for federal funding that goes to the network that broadcasts Probing the Membrane of Science because it's a conflict of interest for her. Meanwhile her rival from the opposing party is married to an oil tycoon who's been accused of illegally dumping thousands of gallons of toxic waste into the ocean but still thinks she can be unbiased about a bill that would make it legal for him to do so and also funnel taxpayer money directly into his bank account. Needless to say, this rivalry heavily mirrors Zim and Dib's.