What version of electrum did he have running? Also, you should be able to go to file and see recently accessed wallet files from there (in case he had multiple and you can only find one specifically). If you meant you found an electrum folder that was empty, you could also try searching for a name like "default_wallet", "wallet" or "wallet_1".

Have you not also got access to his emails if he did pass away so you can see if his funds are on an online account that was his (ie search for "deposit" or popular exchange names where you are).

The chances he actually had 50000 btc are extremely slim, it's not impossible but it's more likely to be a lot smaller than that - it might have been a bluff too.