The last task you will need to do for Gramble to get him to return to the village is to find his two Kweebles. Gramble wasn’t happy about how scared the Orange Peelbugs were after you got them back, so this time he wants you to be able to get them back to him without the need to catch them in your trap.
You can do this by using the Buggy Ball, the Sauce Slinger, and some chocolate. You can find chocolate on a bush to the left of Gramble’s home on the beach. Head left from Gramble’s house and grab the chocolate, then go all the way to the beach. You will find a Kweeble walking around there.
Put the Buggy Ball on the ground, then open the menu with the R1 button and select the Sauce Slinger. Use the right arrow on the D-Pad to change from ketchup to chocolate. Now, fire the chocolate at the Buggy Ball. Roll it to the Kweeble and they will start following it.
All you need to do now is guide the Buggy Ball back to Gramble, making sure to not move too far ahead of the Kweeble, and not get too close to it yourself or it will get scared and run away. If you are lucky, you will pass the second Kweeble on the way back, if you return by the route you took to get to the beach.
If not, all you need to do is walk back to just before you get to the beach when you return the first Kweeble and you will find the second one walking in circles around some rocks and trees.