Given that all lists are unsorted !
therefore we can't apply Binary search,
one way to find median is sorting the list, it takes $Θ(n logn)$, But with out sorting we can find median in $O(n)$.
For one list it takes $O(n)$, then for n-lists it takes $O(n^2)$.
So, now median of every list in our hand !
note that these medians are also not sorted !
Therefore make all these medians as one list, then with in $O(n)$ time we can find the median of medians.
$TC = O(n^2) + O(n) = O(n^2)$.