"Better" in what way? Better as in faster? Better as in less bugs? Better as in more portable? Better as in more readable? Better as in more extensible?
For any suitable definition of "better" arguments can be made either way. However, it is just about sacred writ that no compiled language is more portable than C. Thus, if one of your goals is to make your application highly portable, C is an excellent choice.
More people understand C than Ada. Writing erlang extensions might be much harder if it was written in Ada, simply because fewer people are conversant with the language.
C code can be highly performant, but I am aware of no comparisons between C and Ada w/r to compiler optimizations.
Ada's type checking might be useful, or it could be a real problem. One presumes that a VM does it's own type checking on the pieces that matter to it. The overhead of RTTC in Ada could impose a completely unnecessary burden.