Step 1: Understanding the problem
We know total cost = Rs.\ XY96.7Z, where X and Z are missing digits, and 72 hens share this cost equally.
Step 2: Trying answer options
If each hen costs Rs.\ 5.51, total = $72 \times 5.51 = 396.72$, which fits the missing digits pattern perfectly (3____96.7__).
Step 3: Conclusion
Thus, the only cost per hen fitting the pattern is Rs.\ 5.51.