Something does NOT add up here… If they forgot to install ANY oil, then any “residual” oil, oil left in the engine after it was drained would be pumped into the new filter and there it would have stayed. There would not be a DROP in the crankcase and the engine would have seized up long before 50 miles was driven. Not only does the car have a pressure gauge but it also has a warning light which would have been glowing unless there was oil pressure.
You can demand a new engine all you want, but until you can PROVE engine damage, you will not get one. Get a letter from the dealer admitting their negligence and then wait and see. Any serious engine damage will manifest itself rather quickly…