So, a lightning-plagued cemetery could contain the next Lucy?
More C14 in an organism's remains would theoretically make something old look younger. But the dead are not the ones ingesting the C14. So I don't think it would have any effect on what was measured in the grave yard unless the C14 was somehow put into the structure of the remains.
I am not sure how lightning causing C14 would make much difference unless when the organism was alive it was around lightning so often it had more C14 than other organisms would who were not near where lightning happened. In that case it would make the organism look older than it was....but if this is the case, I would want to know of a study that confirms it before I change my opinion about carbon dating.
What is measured is how many C14 isotopes one has compared to normal carbon atoms. The idea is that there is a certain amount of C14 us living organisms ingest from the environment as we breath and eat. But when e stop living we stop ingesting, and the C14 to regular carbon atom ratio declines as the C14 isotopes become regular carbon atoms at a curved rate of declining decay determined by their half life of around 5730 years.
Thus to estimate age one presumes that there was more or less a certain amount of C14 to carbon ratio in the environment that would come to be reflected to some degree by the organism when its alive, and then one supposes that rate of exchange stops happening when its dead, and we can estimate based on this how long ago it died.