。
She'd better drum the company's policies more thoroughly into her head.
Literal
She [topic-は] company [of-の] policy [object-を] more head [in-に] hammer-in did-side good.
頭にたたきこむ ('beat into one's head') is a vivid set phrase for thoroughly memorizing or drilling in — used for facts, rules, manuals, language vocabulary, anything you should know cold. 頭にたたきこんだ方がいい applies the standard advice pattern V-past + 方がいい ('had better V'), softening the verdict to 'it would be better if she really committed those policies to memory.' The implied tone is mildly critical: someone has noticed she doesn't know them well enough yet.