You can follow the link in my signature to the disABILITIES Board. We have never stayed in the BWV 2 bedroom, but there are disABILITIES Board posters who have.
In general, there are 2 types of handicapped rooms available at most WDW resorts.
One type is a regular room that has some extra things added like grab bars in the bathroom to make it safer for someone with special needs. Other than that, the room is pretty much the same as a regular room.
The other type of room is fully wheelchair accessible with grab bars, and cut out areas under sinks so a wheelchair user can roll right up and use the sink. That type of room also has a roll in shower - basically a tiled area with a drain in the floor. In some resorts, the room will be the same as a regular room, except for the accessibility features. I've been told the BWV fully accessible rooms are bigger in order for someone in a wheelchair to be able to use the bathroom and kitchen.
Think about what her needs will be. If she's generally steady on her feet, but needs the wheelchair for endurance at the parks, you may be just fine with a regular room. If she might benefit from grab bars in the bathroom, the first type of room might do fine.