Nirmala is correct in wanting to say "no" when someone offers her drugs. However, before that happens, she needs to have a plan that helps her to avoid situations that make her vulnerable to drug use and a plan to refuse drugs and maintain her refusal at all costs.
Nirmala can call someone she trusts to formulate this plan with her. The formation of a plan allows Nirmala to be more successful in achieving her goal of not using drugs.