I want to put in the same row a TextView, and Edittext and a button but I am having the problem that the button is not aligned properly to left and in small screens edittext fil
First, many people will tell you that hint is Android's solution for not needing the label. I don't care if you use the label or not but it does save you space, especially on smaller screens. That was just an FYI.
Now, your RelativeLayout that only has a Button appears to be useless...I would remove that. You can use layout_weight so that each View takes up the appropriate amount of space. Make sure to make the layout_width="0dp". So it may look something like
Here I used 2,3,1 for the weights of your TextView, EditText, and Button respectively. You may need to change those to get exactly what you want but that should give you a start.