adverb taking the 'to' particle, adverb
in various ways; in many ways; doing this and that
Describes doing various things for someone, often with a sense of attentive care. Frequently used with と and verbs like 世話をする or 気を遣う.
母は私のためになにくれと世話を焼いてくれた。
My mother took care of me in various ways.
彼は新入社員になにくれとなく気を遣っている。
He is attentive to the new employee in many little ways.
何かと also means 'in various ways' or 'one thing or another', but is more general and can be used for both positive and negative contexts. 何くれ often implies thoughtful, caring actions.
あれこれ means 'this and that' or 'various things', often used when talking about many topics or options. 何くれ is more about doing various considerate deeds for someone.
Compound of 何 (nani, 'what') and くれ (kure, from くれる 'to give'), literally 'what giving'. The exact historical derivation is uncertain, but the word has long been used to express doing various things for someone.