A question that can some times confuse an entry level civil or structural engineer!
Generally, it is not needed to have a top reinforcement for isolated footings. Footings are subjected to the soil pressure and behaves as a cantilever and you need bottom steel for the footings.
Also the footings are buried in soil and is not subjected to any temperature variation. So do we need top rebars for isolated footings?
Here is a video that will completely clarify the requirement of top steel.
You can discuss any additional questions if you have after seeing this video on the minimum top steel requirement for isolated footings.
The rebards mentioned in the video has to be provided both ways at the top face of the foundation.
Also read a blog on foundations here.
Top reinforcement is needed if the footings are subjected to stress reversal due to WIND pressure on columns, causing the top layer of footing subject to Tension.