As the grid gets larger and the agents farther apart, so expands the search space and it will take longer to run. Use a block comment at the top to explain the overall layout of the code, documentation strings at the top of your functions and comments within the code, as appropriate. Help the GTA to understand what you were trying to accomplish. Do not assume that your code is wrong if it returns 'no-solution. This is a stochastic algorithm and may not find the solution.
Stochastic code can be difficult to debug.
So check every step of the way. In fact, the way I wrote this code, I ran every statement in the interpreter to check it before I put it into the file. What to hand in Printed and electronic version of your code, Printed output that shows for each problem the solutions for each trial and the number of moves required for it. The third should be some agent and burger position of your choosing from the 15x10 grid on the right. In all, you will be turning in 10 runs, label each one appropriately.