When you are close, with a scope, you need to aim high, there is not enough distance for the bullet to rise up to the line of sight.
I agree with the above comment, this is the time to fix the scope problem, and thankfully you discovered the problem when it didn't really count.
Start by putting a big piece of paper or board out at 25 yds. Usually, if you are on at 25 yds you will be close at 100 yds.
The bore is usually approx 1.5" below the line of sight, it crosses going up at about 25 yds, and crosses coming down at about 100 yds.