The mother of my gandkids left about 4 hours away, she did not say she was going, she was staying at my son house, my son is in tx. Working right now.. so she has a 2-month baby and a 6 yr. old.. so she would not answer my calls.. so I was worried about my grandkids wherbouts and safety she has post-par.. and very depress so I have done nothing to her, so she is trying to hurt me with the kids and its working.. so also the6 yr. old they did live in mo. They are suppose to have joint cust.. but is it still good here in another state ? So I need some answers

What answers do you need? Your post is very unclear. It sounds like you are saying the mother took the kids and moved away. If this is the case and your son has joint custody, he can file in Family Court to have the children returned. Whether he will win or not depends on the circumstances.