"Miscellaneous" isn't a folder: it's just the category that your phone's storage menu uses for "everything that isn't app, photo, video or music".
I've no idea what those files are. They are probably just media of some sort, but as "MTK" generally means "MediaTek" (chipset maker) I'm a touch nervous of giving a blanket assurance about removing them without knowing more. Can you give some examples, e.g. file name and path (the directory they are in)? That might give more clue as to their significance.