Options after BSc Mathematics Hons are aplenty. You can pursue your higher education, and thereafter a career is teaching can be followed. You can apply for Govt Exams such as Railway,SSC CGL, UPSC, State PSCs based on your graduation degree. Similar to this, is banking exams for SBI, RBI, IBPS etc recruitment for post of officers and clerk.
Depending on your interest in higher studies, you may also pursue MCA or MBA, apart from the traditional path of MSc. And, further work in private companies as well.You can also go for actuarial science, data analysis,chartered accountant etc.