He Ejaculated (came) Inside Me. Can Douching Eliminate Pregnancy Risks?

No.

Douching does not protect you from pregnancy. 

It might actually do the exact opposite and increase your chances of getting pregnant by pushing sperm toward the end of the vagina and the cervix 

If your actions have put you at high risk of getting pregnant, the best thing you can do is to take emergency contraception (EC) immediately. (Learn about EC in the Contraceptives section.) Link