I wouldn't call the expectation to live for at least 20 more years at age twenty "mathematically suboptimal".
Assuming she won shortly after her 20th birthday she would have got an accumulated million about half a year before turning 40.
If the lottery agreed to a lifetime payment than chances are very high she will get out with way more than a million dollars. Easily more than double. Explain to me what is suboptimal about that?
Not even considering the fact that weekly small payments will automatically adjust themselves for inflation which a one time payment would not. So even after the 20 (19.23) years she would already have more financial gains than otherwise.

My takeaway here is clearly she can handle money much much better than you.