I noticed that the B-Class Electric Drive from 2014 I bought doesn't have the Range Plus button on the Multi Switch Panel. I found out this was the only year it was in an optional feature.
I began to wonder what exactly they would do at the factory to enable this option. As a thought...
I found these, for anyone who stumbles on this:
Weather Tech for 2014
https://www.weathertech.com/mercedes-benz/2014/b-class-electric-drive/floorliner-digitalfit/
MB for 2015
https://mbparts.mbusa.com/v-2015-mercedes-benz-b-electric-drive--base--electric/accessories-interior--floor-mats