Turbo C is really old (end of the 80s I think). Can Turbo C code be compiled with the Visual Studio Compiler? If so, you could generate a mex file from it. Not 100%sure but beware that Visual Studio can generate 32bit or 64bit files only but Turbo C generated 16bit files.
Are there converter available which can transform Turbo C in "normal" C?
I don't see any direct way to bring Turbo C into MATLAB.