Assuming you are talking about C++, there is no need for your wife to learn C in order to learn C++.

C and C++ are different languages today, while it is still possible to write C code in C++, it is not recommended.

Last year C++ was "upgraded" with a new standard C++11. If you want to learn modern C++ you will have to use a variety of websites. There is no good beginner C++11 book available for now.

A few useful blogs with C++11 material:

http://herbsutter.com/elements-of-modern-c-style/

http://www2.research.att.com/~bs/C++0xFAQ.html

http://solarianprogrammer.com/categories/C++11

http://bartoszmilewski.com/

A good book about C++ is:

http://www.amazon.com/Primer-4th-Edition-Stanley-Lippman/dp/...

but I would wait for the 5th edition for learning C++11.

If your wife knows nothing about programming I suggest to learn a language like Python or Ruby first ... C++ is not suitable for a beginners.