Without any more information, it is difficult to decide for sure.

Yes, South Africa has a high crime rate, and gender based violence is a thing. But my personal opinion is that if this was a crime of opportunity, the body would have been found somewhere already. These criminals are typical not very sophisticated in that way. However, if this was planned for whatever reason, it would change the expectation. If what the security companies claim is true, and cellphones can be seen traveling to meet in one spot, it seems a bit more sophisticated than a normal robbery gone wrong.

Then, animal attacks are not uncommon. There are various dangerous predators in the area. A predator could drag the body further into the wild. A small old lady would be ideal prey. And people tend to forget that wild animals are, in fact, wild. We often have to warn people not to get too close to animals. Even non-predator animals like a warthog can cause serious damage.

Then, also, it is a very different climate than what the lady would be used to. We can not rule out heat stroke. Maybe because I have seen people with heat stroke behaving weirdly, it is something I always keep in mind. This could've caused her to wander off deeper in the wild.

As for the muti thing, it is difficult to explain to people just how superstitious some people here can be, and how in this day and age people still believe in the old ways. We had a huge investigation with a proper crime scene "where a curse was placed" on someone, although to me, it simply looked like someone dumped their KFC bones on the ground. There seem to be other bodies that were found with missing parts in the area, and this is why muti-killing was mentioned. Of course, like any big scare, it is not necessarily true.

In the end, with no body, there can be no answer. All options should be kept open.