UCs are probably the most realistic options, since they (a) are transfer friendly, (b) do not consider high school stuff (other than fulfilling some base-level check box requirements, though these are optional for admission), © have good in-state financial aid, and (d) should have significant research activity for a math major planning PhD study in math or a related field.
CSUs have (a), (b), and © above, although it appears that there is less emphasis on pre-PhD preparation in math. CPSLO’s career survey indicates that 58 students earned bachelor’s degrees in math in 2014-2015. 22 of these went on to further study, but only 1 to a PhD program. In comparison 12 went to teaching credential programs, 1 to law school, and 8 to master’s degree programs.