@Proterio Do you want a curve with each end of the curve tangent to a circle?
For any two specified points on the circles there are an infinite number of curves which are tangent to the circles to those points. For a NURBS curve the requirement is the first and last control points must be on the circles at the specified points, and the second and next to last control points are are lines tangent to the circles through the specified points.
In regular Rhino you could use BlendCrv with the BlendCrv=PointStart option. I don’t know if there is a Grasshopper equivalent. The result using BlendCrv is a single span degree 3 curve with 4 control points.
Also the curve could be tangent to any point on both circles. There is not a single fixed point for a curve to be tangent to.
This thread may be of help Blending Two Curves