Here are the odd ones out for each set:

1. **(b) volunteer** - The other options relate to actions or people in need, while "volunteer" refers to a person performing an action.

2. **(b) cleaning streets** - The other options (donating clothes, homeless, sick children) are focused on people or groups in need, while "cleaning streets" is an activity.

3. **(d) playing games** - The other options (service, providing food, homeless people) are related to community service or helping others, while "playing games" does not fit that theme.

4. **(b) graffiti** - The other options (donor, contributor, member) refer to people or roles that are typically associated with giving or supporting, while "graffiti" is an action that is often viewed as vandalism.

So, the odd ones out are:
1. b
2. b
3. d
4. b