A great mobility scooter for a person with dwarfism would be:
Scooters
Travel Scoot - named on their wesbite as the world's lightest mobility scooter, they can be made bespoke to people with dwarfism, and they have great experience of working with people with dwarfism. Check out these testimonies from other buyers.
Electric Mobility: Rascal Ultralite 480
These are lightweight, easy to use and can be adapted to make them more suitable for a person with dwarfism.