The displacement is 0.05 meters. The angle between the upward force and the upward displacement is 0 degrees. The work for 1 push-up is approximately. W = 10 N * 0.05 m * cos 0 degrees = 0.5 Joules. If the squirrel does a total of 5.0 Joules of work, then it must have done about 10 push-ups.
