" What would be the value of a set of Can. nickels, about 97, with the '25, and '26 missing from the set?"
Value depends on grade and if there are any higher demand varieties in the group. If they are from 1922 to the present, in VF30 pre 1953, and average circulated from 1953 to 1960, and BU for the rest - perhaps $30 or so. If there are any SP or PR coins, the value goes up. In other words "it depends".