Which size saddle and bridle?
Your daughter weighs 5’1″? Wow! Get a professional saddler out to fit the pony for a saddle. There’s no way to guess just based on her breed! For your daughter I’d guess around a 15 inch saddle, might be different depending on how heavy she is… get her to try them on. A saddle must fit both the pony and the rider, otherwise it will do a lot of damage to the ponys’ back and be uncomfortable for the rider. For the bridle, “pony” is the size you want. Most bridles come in pony, cob, full, and oversize. You need a pony size.