aoa
Firstly ask them to invest in a good motorcycle helmet and at least get the basic motorcycle gear like gloves,jacket,elbow and knee guard.
carry an extra tube,puncture repair kit and rain gear.
Mostly there are motorcycle shops along the way but in some areas it will be hard to find like between chilas and raikot.
And please ask them to do not hurry rather enjoy the ride and avoid overtaking on sharp turns.