Final answer:
After Ragnarok, Vidar and Vali do not find a specific object from the options provided. There isn't a widely recognized artifact tied to them post-Ragnarok in Norse myth.
Step-by-step explanation:
The question asks which object Vidar and Vali find after Ragnarok. None of the options listed (Gungnir, Mjolnir, Gleipnir, Megingjord) are associated with what Vidar and Vali find post-Ragnarok.
In Norse mythology, it is believed that after Ragnarok, the world will resurface anew and fertile, and from the ashes, the surviving gods would find two human survivors. There isn't a specific artifact associated with Vidar and Vali in the surviving mythic sources, such as the poetic Edda or the Prose Edda, that they find after Ragnarok. It is important also to mention that different sources and interpretations might vary, and Norse mythology has many versions of stories where details can be ambiguous or lost over time.