I am the biological mother of a woman born in 1967.
To substantiate birth records for her and to prove that I am her biological mother, what is BEST DNA testing?
The best test to prove or disprove parentage is a standard autosomal test at any of the major DNA testing companies that provide you with your matches.
A child gets one chromosome of every pair from each parent and you will therefore match with your parent completely on every chromosome. All testing companies will identify this correctly as a parent/child match and will not mistake it with any other relationship. Other than a rare testing or lab error, it is pretty well 100% reliable for parent/child.