何から何まで means "absolutely everything", "every last thing" – word for word "from what to what". It works as an adverb in front of the verb and says that nothing was left out.
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Thank you for taking care of absolutely everything.
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She does absolutely everything by herself.
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When I moved, my friend helped me with absolutely everything.
The first sentence is a set phrase. You say it on leaving, to a host or a colleague who has looked after you, and does the same job.
何から何まで or 全部
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state "all". 何から何まで stresses that every detail is included, which makes it warmer in thanks and sharper in a complaint.
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I hate having my parents decide every single thing for me.
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My mother meddles in every single thing.