speaking only on eyre here: the family is trundled off together in a cart at the end - however, just because they are dead DOES NOT constitute nihilism. for the ending to be nihilistic there must be a sense that nothing had a purpose - not just that there death had no purpose but that their life didn't either. it's not a redemptive ending certainly - but its not nihilistic either. eyre does attempt to show that the filial bond between Lear and Cordelia has been repaired, and even the fact that the whole family is on the one cart adds to the theme of the importance of the nuclear family unit. Eyre shows the importance of these bonds and that, even with death, these bonds are still in place. So, no, the ending is definately not nihilistic.
just out of curiousity, why do you ask? a nihilistic reading is not one commonly imposed on eyre's production - more common being domestic and psychoanalytic.