when there isn't a ground wire , is it ok to ground to the neutral on a outlet?
No.

The usual solution is to replace that outlet with a GFCI outlet, attaching the included label to indicate that it is ungrounded. This provides equivalent protection, perhaps better.

In older buildings where the wires run in metal conduit, the metal outlet box is grounded through the conduit. The prong outlets are designed so they can ground to this through their mounting tabs, though some of us prefer an actual wire between the ground terminal and the box. This is traditional and it should work as long as all the conduit and box connections are secure.

Or install a GFCI and make sure it is properly grounded. Belt and suspenders.

But do not connect ground and neutral at any point except the main breaker box, and do not try to use neutral as a ground.