Here are the corrections for the underlined parts:

1. **What he detests to do is going to work at weekends.**
Correction: D (should be "is to go")

2. **All the girls in my class are a big fan of SNSD girl-band.**
Correction: A (should be "are big fans")

3. **Going fishing alone is one of my Dad's favorite leisure activity.**
Correction: C (should be "activities")

4. **She sings that song much more better than I do.**
Correction: B (should be "better" instead of "more better")

5. **I think that she wouldn't mind to go to the night party with you, surely.**
Correction: A (should be "going" instead of "to go")