Preeti starts from point A and drives $7\text{km}$ towards South. From here, she turns left and drives $9\text{km}$. Then she turns left one last time and drives $7\text{km}$ to reach point B. How far should Preeti drive to reach point A from point B?

Let's trace Preeti's path step by step:
1. Starts at point A and moves South for $7\text{km}$.
2. Turns left (which faces East) and moves for $9\text{km}$.
3. Turns left again (which faces North) and moves for $7\text{km}$ to reach point B.

Since both the southward and northward paths are equal ($7\text{km}$), point B lies exactly East of point A. The shape formed by her path is a rectangle where the opposite horizontal sides are equal.
Therefore, the distance between point B and point A is equal to the horizontal distance covered, which is $9\text{km}$.