In intl F class often there is no "vegetarian meal" but there is a vegetarian choice; e.g., When ordering for friends, I was told by AA that there were no vegetarian meals on flights to South America, but they found that there was a pasta option that had no meat served in Biz class.
It is likely that your parents did not know the difference and were unable to recover from this irregularity once the "vegetarian meal" was not found.
Certainly 10k is OK; If the whole trip was say 90k, 10k for the food seems reasonable.
The problem often is that if you do not tell the purser of FA at once after boarding, the option often gets ordered by someone else and you have no choices left for you. AA and UA have been great for us at getting the issue fixed, if we tell them as soon as we board for special meals.
In one instance my friends ordered Veg meals and after getting on board fell asleep on a 6 AM BWI-SFO UA flight. The FA came to serve them first ad finding them asleep, served the others this choice (or so she claimed later).