Answer:
Let's break this down: initially, there are 34 people in the yard. You were in the garden, which is presumably a separate area from the yard. When you killed 30 people in the yard, there would be 4 people remaining in the yard. Since the problem states that you were in the garden, you would still be in the garden.
The number of people in the garden would depend on whether any of the people from the yard moved to the garden or not. If no one moved, and assuming you were the only one in the garden initially, then there would still be just you in the garden. However, if some of the 4 remaining people moved to the garden, the count would increase accordingly. Thus, without further information about movement between the yard and garden, the garden would still have you, making it a total of 1 person.