Could you try to run with a debugger? This might help http://www.isi.edu/nsnam/ns/ns-debugging.html

A segmentation fault is caused by your program attempting to access memory that it has not been allocated. Typically this would result from trying to use a dynamically allocated data structure which has been freed (or deleted in C++), reading or writing beyond the end of an array etc. I'm not familiar with this particular simulator, but you may have found a bug in it - if you are just constructing a scenario in a script and running it using a provided binary this will be the case (they may have forgotten to do some checking of the values you provided). If you are coding in C or C++ (for example) then you could use a tool such as Valgrind to help track down the problem.

Following Daniel's comment, I would add from my experience with NS2 that this is a typical error in Adhoc simulations. I never worked with AntHocNet but probably there might be some limitations in the default settings related to number of nodes you can use with AntHocNet. That setting is usually used to allocate memory for routing tables and other data related to routing. Check the files under AntHocNet directory for any configuration file or usually they put these kind of variables in header files.