You shouldn't need many vaccines. Just the standard vaccines that everyone always receives during life (at least here in Canada) Hepatitis A & B, Meningococcal meningitis, Tetanus/Diphtheria, Typhoid etc. Then I believe the only other one you need is Yellow Fever and the yellow fever vaccine is a must! They may recommend you get Rabies and Cholera vaccines as well. Also be aware of Malaria...I do believe if you are above 4000ft or 5000ft malaria is not a concern. So generally speaking it isn't a massive concern in many parts of Kenya. It is still something you should be prepared for though!
I don't know if you have them in the US but go to a travel medical clinic. Here we have clinics that only focus on people who are traveling. You have an assessment with a Doctor, you explain where you're going, for how long etc. Then they explain what you need to be aware of (health wise) and what vaccines they recommend for you. You then have a nurse give you the vaccines and give you any other products you may need...i.e. Deet insect repellent, mosquito nets, travel first aid packs etc