What should i do if my mom has a tntc in her urinalysis and she also has a low platelet count? she's not allowed to eat dark food. what food can she eat?

I would have her treatment team assess the situation. TNTC white cells in the urine suggests a UTI but may be inaccurate depending on how the sample was collected. The diet she is allowed is best determined by those who know her complete history/exam and testing results.

You did not say TNTC of what? best is to repeat the test with a mid-stream clean catch specimen and go from there.