"My daughter often helps me."
Translation:Moja córka często mi pomaga.
nie pomaga mi has no accent on mi, so it's ok.
Mnie nie pomaga is accented and correct while Mi nie pomaga is accented ad often said but frowned at
but the whole point of putting mi/mnie at the end of the "Moja córka często pomaga mi/mnie" is accent.
Which takes us to a point that proves such sentence very uncommon.