both state and edge
because
let in M edge label (transition) define such as a,b,c but in N it may be different such as x,y,z (but M and N both are isomorphic because isomorphic does not care about label) so we have to change the label
for state explanation
no of final state in M and N can be different means m can have 2 but N can have 3 etc but both are isomorphic
we have to change them