Amphoteric oxide(s) of Mn is/are:

Amphoteric oxide is ${\mathrm{MnO}}_2$. It contains Mn in the + 4 oxidation state. It reacts with both acid and base.
${\mathrm{Mn}}_2{\mathrm{O}}_7$  is a weakly acidic oxide. It contains Mn in the + 7oxidation state (highest oxidation state). It has covalency with O atoms that are covalently bound. MnO is an elementary oxide. It contains Mn in the +2 oxidation state (low oxidation state). It is oxide that is ionically bound.