Rub the edge or corner of a 100-grit sanding block along the dried adhesive. Be careful to keep the sanding block in contact with the dried adhesive only, and not the wood floor.
Continue in this manner until you remove all the dried-on adhesive and then run a 220-grit sanding block over the now clean wood, to smooth it out.
Wipe down the area with a tack cloth, to remove the dust from sanding. Moisten a soft cloth with lemon oil and rub it into the area. Allow it to dry completely.
Dip a 1-inch nylon brush into the type of finish that is on the rest of your floors and apply a very light coat to the spots where the adhesive was. Allow it to dry overnight.