This ending completely misenterptets the end. Theyre supposed to be happy that Gregor, a burden on their family since he could'nt work, is finally dead, so they go on a vacation to celebrate. The lazy parents though will need a new source of income now that Gregor is dead, and theyre going to exploit Grete the same way they exploited him. The parents are supposed to be standing ominously in the background discussing this like in Nishioka Kyoudai's version.