I have an older house without ground wires in the wiring. I want to install a gfci end of the run receptable in a bathroom. I have access to power via the bathroom light. There are no ground wires in the box What will I need to do to install the gfci receptacle? Can I install without the ground wire? Will need to come from my main panel box which will be difficult? Can it be grounded to the outside via a pipe in the ground? The bathroom is on an exterior wall.

A bathroom receptacle must be on a 20A circuit and be GFI protected.
If the circuit you are thinking about has more items tna just that one bathroom (which is highly likely) then you CANNOT use it for a bathroom receptacle feed.
Besides, we are not allowed to extend an ungrounded circuit.

IMO a new 12/2 run from the panel is your only (and best) option.

Stanforyman - I was under the impression that the only legal way to replace an old 2-prong outlet when the cable feeding the box has no ground is with a GFCI - isn't that correct? You would mark it as ungrounded, but the GFI would still work properly, providing protection against electrocution hazard in the bathroom. Is that not correct?

This is certainly true, but the OP wants to extend an ungrounded circuit to install a new receptacle. Even if this is a GFI it is not allowed nor is it a good thing to do.

This is certainly true, but the OP wants to extend an ungrounded circuit to install a new receptacle. Even if this is a GFI it is not allowed nor is it a good thing to do.

Got it - I missed the bit about wanting to extend the existing run. Thanks for the clarification.