This is a very hard question to answer. It is very difficult to know how to get past the legacy of racism and the problems of economic inequality to protect these farmers.
One way to protect them, of course, would be to increase police protection for them. However, this is probably impractical. Police cannot work as security guards for specific people. There is no way that they can protect people from harm on a constant basis if there are people who really want to harm specific individuals. It is simply not possible to devote the sorts of police resources that would be needed.
Ideally, the South African government would do more to help bring about economic development in the rural areas of South Africa. This might make it less likely that farmers would be killed for economic reasons. It might also reduce the level of racial resentment still felt by black South Africans over the country’s racist past. Economic development, of course, is more easily spoken of than accomplished.
Another possibility would be for the South African government, and the ANC in particular since they are essentially the same thing as the government, to speak out strongly against racial hatred. The ANC, perhaps understandably, tends towards black nationalist rhetoric at times. If it would be more outspoken about the idea that it represents all South Africans, that might be helpful as well.
Overall, however, it will be very hard to help white South African farmers as they are very vulnerable and there are strong motives to attack them.
Your question is , as pointed out at Ans.#1, a difficult question to answer. I would also suggest that the notion of a "white" South African farmer is in itself problematical!
Historically, South Africa has many "white" farmers, as they had the funds to purchase the land and the expertize to manage the farms. Unfortunately, some "white" farmers were extremely radical - I say "were" as they are the exception not the rule in a modern South Africa. Although there are, sadly, still many unresolved issues in SA, the white, militant farmers are largely a thing of the past. Most "white" farmers in SA were born in SA and obviously they have as much right to its heritage as anyone.
Unfortunately though, the economic inequality and thus hardship suffered through Apartheid has left many bitter, resentful and vengeful people in its wake - some of whom never even knew apartheid (aged 15 to 18). The age group of the offenders is often very young. They target "white" farmers or anyone in fact, from their perspective of ignorance.
The very fact that a person is "white" and a farmer should not suggest that he belongs to an elite club. There is a crime problem in SA but "white" farmers are not the only ones suffering. When farmers are murdered, it is criminals - NOT freedom fighters!- who perpetrate the crime. Race is only important insofar as "whites" are responsible for all the problems(in their minds) and so..... The crimes are often heinous and whole families have been wiped out on occasion. They are often in remote areas and criminals have no concept of the "bigger picture" or human rights.
SA has problems with immigration as many "struggle comrades" allowed exiled members of , largely the ANC, to sequester there when hiding from the SA government in the 1960s. These , mainly African countries want "pay back" and make large demands on the SA government which the government feels obliged to meet. Hence, large numbers of immigrants arrive in a country where there is a problem with unemployment, poverty and where distribution of wealth is a big issue. On a large scale, maybe better immigration control would help.
Job creation is somewhere that many South Africans try to contribute ; hence there is less mechanical equipment and more manual labor. This however creates its own set of problems with workers' demands, cultural differences, etc.
There are many schemes in place to help Black farmers to start and run successful farms. Resources are often a problem and corruption does raise its ugly head as some use the designated funds for the wrong purposes. This is one way, however that the government is trying to help. It may not directly help "white" farmers but it does increase the faith of most South Africans. Some "white" farmers however feel marginalized and their bitterness comes across as arrogance. So misunderstanding is commonplace.
Private security firms are very big business in SA and using these firms to patrol the perimeter of their farms or installation of better security measures helps but sometimes the criminals ARE the security guards!!
For me, though, the biggest help for ALL South Africans is EDUCATION, ACCEPTANCE and SOCIALIZATION. This includes the need for a secure Justice system, less corruption and adequate policing as part of the socialization process. If we educate everyone adequately and punish appropriately, we can continue striving towards Nelson Mandela's vision for South Africa, the "Rainbow Nation. "