**nosey** and **busybody**. less formal, colloquial names for such person(s).

As in;

> *Nosey* and *busybody* are names for a person who people insist on giving
> you help/advice you didn't ask for?

[nosy][1]
[busybody][2]


  [1]: https://www.thefreedictionary.com/nosy
  [2]: https://www.thefreedictionary.com/busybody