Explanation:

- Let's say the original total daily expenditure of the mess is Rs \( X \).

- Original Scenario:

- Number of students: 45

- Average expenditure per student: Rs \( \frac{X}{45} \)

- New Scenario after increase:

- Number of Students: 50

- New total expenditure: Rs \( X + 30 \)

- New Average expenditure per student: Rs \( \frac{X + 30}{50} \)

- The condition given is the new average expenditure decreases by Rs 2:

$$

\frac{X}{45} - 2 = \frac{X + 30}{50}

$$

- Solving this equation:

- Multiply through by 2250 (LCM of 45 and 50):

$$

50X - 4500 = 45X + 1350

$$

- Simplify:

$$

5X = 5850

$$

- $$

X = 1170

$$

- Therefore, the original total daily expenditure is Rs 1,170.

- So, the correct option is:

Option: 1 - Rs 1,170