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She didn't say a single word to me.
Literal
She [topic-は] me [to-に] just one-word-[even-も] said-not.
ただの ('a mere, just a') intensifies a minimum: ただのひとこと = 'just a single word.' Combined with も and a negative, the whole expression turns into the universal negative 'not even one word.' This is a generalization of the [counter]も+negative pattern (一日も来ない 'doesn't come even for a day,' 一円もない 'don't have even a yen'). The structure conveys not just absence but pointed absence — she could have said something, even minimal, and didn't. The hurt is in the gap.