My grandparents were both born in Holland. My aunt and uncle (Mother's siblings) were born in Holland. My aunt has a Dutch passport. My mother (deceased) was born in South Africa (1951) My father (deceased) was born in South Africa (1949) I was born in South Africa (1980)
I would like to know if I qualify for a Dutch passport.
You may be eligible to apply for Dutch nationality by option, but this is only the case if your mother retained her Dutch nationality until you were born.
There are two questions here. The first is whether you are a Dutch citizen now, and the second is (if you are not) whether you have any way to obtain Dutch citizenship other than the residence-and-naturalization route that is available to everyone in the world, where getting a residence permit is usually difficult.
For the first question, you were Dutch from birth only if your mother was unmarried and (if I recall correctly) your father did not recognize you as his child. If we assume that your parents were not married, then you were not Dutch.
The discrimination of Dutch nationality law on the basis of sex was removed in 1985, but not retroactively. In 2011, a new provision was added as a partial remedy, allowing so-called "latent Dutch," that is, people who would have been Dutch if their Dutch parent had been their father instead of their mother, to obtain Dutch nationality through an "option procedure."
For you to qualify for this option procedure, your mother must have been a Dutch national when you were born. She almost certainly was Dutch when she was born, so the question becomes whether she lost her Dutch nationality before you were born. This would have happened ten years after she reached the age of majority, for there was (and is) a rule that someone who lives abroad for a period of more than ten years loses Dutch nationality. The specific circumstances triggering the rule have changed over the years; if I understand correctly, between 1892 and 1985 it applied to people who were born outside of the Netherlands, so it would have applied to your mother.
If this analysis is correct, depending on when she reached her age of majority, she would have lost her Dutch nationality at some point between her 28th and 31st birthdays. The age of majority was lowered from 21 to 18, for most purposes, in 1988, but it was lowered to 18 for the purpose of nationality law at least when the 1985 law came into effect. It may have been earlier.
Since you were born before your mother's 31st birthday, there is a good chance, therefore, that you qualify for the option procedure. Details may be found at the relevant page of the Immigratie- en Naturalisatiedienst, where you are (possibly) covered by the 8th point in the list.
There is also more information at Applying to become a Dutch citizen via the option procedure at netherlandsworldwide.nl. Note again that this depends on your mother having retained her Dutch nationality at least until you were born.
Proving your mother's Dutch nationality could be difficult. You will probably need her parents' birth certificates and hers, at least, as well as yours. You will also need to prove that your father was not Dutch, though his birth certificate might be sufficient for that.
