search based on Tree level or based on URL

Hi, 

i have a site with pages like this structure.

a

b

• c
• d
• e

f

• g
• h
• i

suppose if am browsing c page and i click serch button, then i want to display serch results under b level tree.dont want to display f tree level results.

suppose if am browsing g page and i click serch button, then i want to display serch results under f level tree.dont want to display b tree level results.

or 

otehrwise is there any option to filter GetResult() after search hits.