How to find the nearest surface (a single surface) of the surface list (index)

Hello everybody! I have a problem. I have a list of surfaces and one surface as an index to find the nearest surface from the list? I tried every surface to find the center and at a distance to find the closest point, but the problem is that the list of points has nothing to do with the list of surfaces, and the index of the nearest point does not coincide with an index surface  :( 

Thanks