Collinearity between categorical and continuous variables is very common. The choice of reference category for dummy variables affects multicollinearity. It means changing the reference category of dummy variables can avoid collinearity. Pick a reference category with highest proportion of cases.
VIF is not a correct method in this case. VIFs should only be run for continuous variables. The t-test method can be used to check collinearity between continuous and dummy variable.
We can also safely ignore collinearity between dummy variables. To avoid high VIFs in this case, just choose a reference category with a larger fraction of the cases
