Why did Qui-Gon and Obi-Wan return to Naboo?

Question

Qui-Gon and Obi-Wan are sent to Naboo in order to force the Trade Federation to make a peaceful agreement with Queen Amidala. When the invasion occurs, they decide to take Amidala to Coruscant to meet with the Senate, and inadvertently have to stop at Tatooine. After they finally make it to Coruscant, Amidala decides to go back to Naboo to fight back against the Trade Federation. However it's not until she is aboard her ship, seemingly entering her own system, that she starts to explain her plan to her subjects and the Jedi. My question is, why did the Jedi return to Naboo with her in the first place?

It seems that they were tasked with finding Darth Maul, but Darth Maul was not sent to Naboo until Palpatine heard the Jedi were returning to Naboo.

Answer 1

Because the Council said to

The script makes it pretty clear. The Jedi Council is talking about the assassination attempt made and that Queen Amidala was evidently in danger:

QUI-GON : ...my only conclusion can be that it was a Sith Lord. MACE WINDU : A Sith Lord?!?

KI-ADI : Impossible! The Sith have been extinct for a millenium.

YODA : The very Republic is threatened, if involved the Sith are.

MACE WINDU : I do not believe they could have returned without us knowing.

YODA : Hard to see, the dark side is. Discover who this assassin is, we must.

KI-ADI : I sense he will reveal himself again.

MACE WINDU : This attack was with purpose, that is clear, and I agree the Queen is the target.

YODA : With this Naboo queen you must stay, Qui-Gon. Protect her.

So, they went to Naboo because they were operating under the orders of The Jedi Council.