I can’t say much about the neurotransmitters and hormones, which are peptides or small molecules. These chemicals can have a wide range of stabilities, to being stable in the fridge to being so unstable that it is difficult to extract them from tissues before they degrade.
In the frozen environment, a number of factors are operant. The cold temperature reduces the chemical reaction rate, which slows down degradation of unstable molecules. Most proteases (proteins that destroy other proteins) are inactive at very low temperatures, however, some still have very low activity, meaning that they will destroy small proteins and peptides even in a frozen sample.
The only way to know if the important neurotransmitters and hormones would survive being frozen long-term would be to test long-frozen neural tissues to see if those molecules are still present, and in concentrations comparable to those found in living tissues.
I wonder where I can get a bet placed against them managing to resurrect this person. 50 years of being frozen I would think that the damage to the peptides etc is massive.