Ans: B. Interossei and lumbricals
Hyperextension of metacarpophalangeal joint and flexion of the
interphalangeal joint is due to palsy of lumbricals and interossei
muscles.
The action of Lumbricals: Flexion of MCP, Extension of IP joint
The action of Palmar interossei: Adduction of fingers
The action of Dorsal interossei: Abduction of fingers
Ref: BDC, 7th edition, volume 1, pg no. 163.