Ok, look: One isolated molecule of benzene contains 6 C-H bonds and 6 C-C bonds. You could theoretically form these bonds from 6 lone carbon atoms and 6 lone hydrogen atoms, all in the gaseous state. Whatever energy is stored in a benzene molecule from a starting state of 6 isolated carbon and 6 isolated hydrogen molecules goes into forming those bonds. You have to use gaseous states here because condensed phases have intermolecular energies to worry about. (The problem uses moles of molecules, but the idea here is the same.)
Represented by a chemical equation, this is 6C(g) + 6H(g)
You have to assemble all those other pieces of information to find out the enthalpy change associated with this process. Your starting point, which is the tricky part to see, is the enthalpy of formation of liquid benzene. The enthalpy of formation has a very specific definition. I suggest you look up the definition of the enthalpy of formation, and write a chemical equation as it relates to benzene. You can be pretty sure it will involves some of the species in the equations you are given, and I suggest you keep close track of the phases of matter, because that's important. Then you can use a standard Hess law approach to determine the delta H of the above reaction.
There's one more logic step after that, but see if you can get to that point and the rest isn't too hard.