Nobody bought tickets in the bus (option 'C').

Explanation:

Introduction:
The question asks who bought tickets in the bus, and the correct answer is option 'C', which states that nobody bought tickets.

Analysis:
To understand why nobody bought tickets, we can consider the other options and eliminate them one by one.

Option A: Amma
The option 'A' suggests that Amma bought tickets in the bus. However, the question does not provide any information about Amma buying tickets or being involved in any way. Therefore, option 'A' is incorrect.

Option B: Children
The option 'B' suggests that children bought tickets in the bus. Again, the question does not mention anything about children buying tickets. As such, option 'B' is also incorrect.

Option C: No one
The option 'C' states that nobody bought tickets in the bus. This answer seems plausible because the question does not provide any information about anyone purchasing tickets. Therefore, option 'C' is the correct answer.

Option D: Abba
The option 'D' suggests that Abba bought tickets in the bus. However, just like the other options, there is no mention in the question about Abba buying tickets. Thus, option 'D' is incorrect.

Conclusion:
Based on the analysis, we can conclude that nobody bought tickets in the bus, as the question does not provide any information regarding ticket purchases. Therefore, the correct answer is option 'C' - No one.