With a little knowledge,you don't have to be intimidated about picking out gifts for special needs children.
Athough I can't give you a "one toy fits all" recommendation, I can suggest some general guidelines to make the process easier as well as gifts for children with specific challenges:
GIFTS FOR CHILDREN WHO HAVE A HARD TIME PICKING UP SMALL OBJECTS OR ARE CHALLENGED BY FINE MOTOR ACTIVITIES:

 Look for items such as puzzles which have LARGE knobs so they can be picked up.
Sample items which may be appropriate:
  Puzzles with knobs
  Geometric tracking Boards - allow tracing of shapes using large, manipulatable knobs
  Motor Shapes Sequencing boards
  Adapted toys, such as Jack in the Boxes which don't require a key to be turned but pop up by simply touching a special knob or items which start when a child blows lightly on them. Some toy manufacturers offer regular and adaptive toys.

Read aloud Books which include children with disabilities  or in wheelchairs etc
 Sample Titles include:
 A Very Special Critter - Mercel Mayer (main character is in wheelchair)
 Someone Special Just like you
 Lee, The Rabbit with Epilepsy

Resource books for Parents
 Creative Play Activities for Children with Disabilities
  Inclusive Games
  Games for People with Sensory Impairments