Depending on what functionality you need, it may be plausible to interact with an Apache Fuseki server via the SPARQL 1.1 Protocol. Fuseki is Jena, just wrapped in a Jetty service in order to implement the protocol.
If this is far heavier than what you are looking for, and you desire interacting with Jena from C/C++, then JNI (or better yet, some automated wrapper like SWIG) may be your best bet.