A boy presents with an injury to the medial epicondyle of the humerus. Which of the following would not be seen -
Medial epicondyle fracture causes injury to the ulnar nerve.
In ulnar nerve palsy only following muscles of 3rd & 4th fingers are paralysed:-

i) Palmar & Dorsal interossei
ii) 3rd & 4th lumbricals
iii) Hypothenar muscles

However, extensors of these two fingers are not paralysed which are supplied by the radial nerve.

About other options

The weakness of ulnar deviation & flexion is due to paralysis of FCU and medial half of FDP.
There atrophy of hypothenar eminence and sensory loss over the hypothenar area.
Weakness of the ulnar deviation and flexion
Complete paralysis of the IIIrd and IV th digits
Atrophy of the hypothenar eminence.
Decreased sensation of the hypothenar eminence