。
She was a great help to me.
Literal
She [topic-は] very my help [become-に] became.
助けになる ('become a help') is the standard frame for 'be helpful' — Japanese expresses helpfulness through becoming, casting the helper as transforming into the role of help rather than performing help as an action. The same X+になる pattern produces 力になる (become a strength → be a source of support), ためになる (become for-the-sake-of → be beneficial).