Do you have the MB chassis manual for your year (2015?) of cab chassis under your motorhome? If not, download one and it will have an inventory of parts included in your tool kit. It might be the towing eye bolt that goes into the pop out hole in the front bumper. Looks about the right size. Just a guess, as I've never looked at mine.
You can verify the chassis buid date by using one of the online MB VIN decoders. Plug in your VIN and see what it tells you.
2018 (2017 Sprinter Cab Chassis) Navion24V + 2016 Wrangler JKU (sold @ ????) - 2016 Sunstar 26HE (sold @ 4600 miles) - 2002 Roadtrek C190P (sold @ 315,000kms)