Nope. That isn't it. You're right, of course, that H^+ will increase because you are add so many H^+ with the HCl. BUT, this H+ you are adding is a "common ion" to the H^+ in HF. Remember HF is a weak acid.
HF ==> H^+ + a = (H^+)(F^-)/(HF) = about 7E-4
So when you add H^+ to this (the common ion), Le Chatelier's principle says the reaction will shift so as to undo what we've done to it. Since we've increased the H+ by adding HCl, the HF reaction will shift to the left to decrease it's contribution of the H^+ which makes b the correct answer. HF gets slightly larger; H^+ (from HF) gets slightly smaller.