Logic is a small part of philosophy though, and the logic used by computers is more like maths than philosophy.
True, but given that question is about what to combine with philosophy that's not very helpful. I'm simply pointing out that, in my experience, there are certain parts of philosophy (logic, philosophy of mind) that are complementary to computer science. I'm not saying that computer science is the most complementary subject nor I am saying that other suggestions like law and politics are inappropriate. I think it depends which area of philosophy you're most interested in. For those interested in 'fluffy' philosophy (e.g. moral and political philosophy, aesthetics), I would suggest combining this with a social sciences or humanities subject (all of which will be classified as 'useless' by Kayla's father - with the possible exception of law and economics). For those interested in 'trouser' philosophy (e.g. metaphysics, epistemology, philosophy of mind, philosophy of science), I would suggest combining this with a natural science (all of which will be classified as useful by Kayla's father).
Interestingly, many of the people we now regard as great twentieth-century philosophers were originally trained in other disciplines, e.g. Wittgenstein (engineering), Russell (mathematics), Frege (mathematics), Carnap (physics), Goodman (art dealing!).