Here are the best options for each sentence:

3. I cut **myself** shaving.
**B. myself**

4. Do you mind if I take **myself** home now?
**B. myself**

5. I helped **myself** to some food.
**B. myself**

6. I wanted to do it **myself**.
**B. myself**

7. He's so ill he can't dress **himself**.
**B. himself**

(Note: Numbering was adjusted to match the questions appropriately.)