Dude, benzene is nasty carcinogenic plagueified shit, it is however, still non polar.
And despite this, you're more than happy to contemplate playing with carbon tetrachloride or worse, flourine gas, phosphines, and so forth... not a flame, but you should perhaps have a think about relative risks... Benzene is perfectly safe if handled with moderate care in a decent fume hood.
As to the original question, benzene and xylene are likely interchangeable anyway, so a combination of the two, for this purpose, shouldnt cause a problem that I can see... "hydrocarbons" would likely mean alkanes that boil at roughly the same range as benzene or xylene, which just means it hasn't been thoroughly purified... however, for an extraction it should be fine. All of the three are non polar, so it should be all good. If you're seriously worried, you can always try a small scale work up to be certain.