I am repairing my parents old single lamp (lamp F30T12-CW) ballast (old ballast was a GE 6G1075) with a two lamp ballast ( Phillips Advance B134SR120M-A) but only connecting one lamp The new ballast has 2 blue, 2 red, 2 yellow plus black hot and white common... what wires do I connect to the tombstones? Thank you
You don't, unless the ballast label or data sheet says you can.
In your case the ballast label says "For 1-lamp operation, individually insulate the yellow leads for 600V" - that is canonical. Further, it makes sense. They need to be capped off from each other because there is preheat voltage on them.
Since you need 4 wires and there are 4 wires left, do the obvious. The red wires go to the same end, because they provide lamp preheat for that end. That's what makes it a rapid-start ballast and not instant-start. Despite the names, rapid-start is better - it starts more reliably in the cold, and lamp life is much, much longer - because it starts the tube using its preheat feature as intended.
This does not mean you can do this 1-lamp trick for any rapid-start ballast. Many do not support it. You got lucky, don't chance it again - check the label or data sheet. Labels typically list some of the tubes supported; data sheets list every one.