Does Mandos have jurisdiction over men?

[Susan Delgado]

I do not think dwarves went to the Hall of Mandos either. I am pretty sure Gimli is the only dwarf to set foot in the undieing lands.

First, going to the Halls of Mandos is different from walking in the undying land while still alive. Second, your premise is countered by this, from the Silm, Chapter II, "Of Aule and Yavanna"

Aforetime it was held among the Elves in Middle-earth that dying the Dwarves returned to the earth and stone of which they were made; yet this is is not their own belief. For they say that Aule the Maker, whom they call Mahal, cares for them, and gathers then to Mandos in halls set apart; and that he declared to their Fathers of old that Illuvatar will hallow them and give them a place among the Children in the End.