What has better prospects: A History degree or History and Spanish?

There are an infinitesimally small number of jobs that are 'must have a degree in History' but plenty where 'must have language skills' is vital. Spanish - and a year abroad - will add enormously to your graduate CV.

So do you think I should do a language degree, like Spanish with another language? Or do you think History and Spanish is alright (this entails a year abroad in spain/latin america)? Thanks for the reply!

History with Spanish - and study abroad in Latin America?
YES - grab it with both hands!

Go with your heart and do the dual. International relations isn't just about knowing a language and another culture - history will give you a perspective on learning from the lessons of the past, as well as research skills and how to evaluate evidence.