You will need to go to
Federal Taxes->Health Insurance (at the top) to start the interview on health insurance.
You will need to answer the questions, because while the interview does ask you if you thought the premiums were too expensive (there is a check box for this), there is, in fact, a mathematical calculation defined by the Affordable Care Act to determine if the premiums were "too expensive"
And this calculation will vary based on whether your mother is a dependent of yours or you of hers or if there are other people in the tax family and what the household income is and so on.
TurboTax will do its best to guide you to an exemption, if you (or she) qualify.
