GPS Failure

Can we make our vehicle to return to the Home position or follow the current mission after GPS Failure?

Both yes and no.
So if you lose GPS signal, the vehicle won’t know how to return home or follow the current mission, since that is what the GPS is supposed to tell it. Therefore, you won’t be able to do it if you only have a GPS.
But there are other ways to navigate in areas without GPS, which you have to research yourself, that you can use as a backup in case the GPS fails, but this is challenging to do.