Do you want to keep the same buttons but have them in one column instead of separate columns? If so, you could remove the borders between the columns using CSS - it would then look as one column with all buttons combined, although technically it consists of three columns.
If you want three buttons but in a smaller column, you can also consider leaving out the button text and use only an icon. Again, using CSS you can reduce the margins around those icons and make them appear to be in one column.
