The most likely explanation for the results is:
Naveed’s object had greater kinetic energy.
When objects are dropped from a height, their kinetic energy upon impact, which is influenced by both mass and velocity, affects how deep they penetrate into the sand. Since Naveed's object created a deeper hole than Maddie's object, it indicates that Naveed's object had more kinetic energy at the point of impact, which could be due to greater mass or potentially greater velocity at impact if factors like air resistance are negligible.