Very difficult to bleed all the air out, sometimes lifting the front of the vehicle up as high as possible, safely, will help during bleeding.
To isolate whether it's a mechanical or hydraulic failure. If the pedal is stuck to the floor but can't put it in gear, that says hydraulic to me, air still in system. If she can put it in gear and then the truck goes when she gets it unstuck, I'd say mechanical.
Free play may need adjusted but playing with mechanical adjustments are typically not needed, I would force fluid and air from the end of the system back up to the reservoir while its jacked up high in an attempt to bleed the air out. I have also installed bad new parts.