It depends on what a "rumbus" is.
A rhombus has 2 pairs of opposite parallel lines
A nephroid has 2 lines of symmetry.
it has five lines of symmetry
10 lines of symmetry
4 Lines of symmetry
2 lines OF SYMMETRY
2 lines of symmetry
It has 2 lines of symmetry.
no lines of symmetry
2 lines of symmetry
5 lines
There are infinitely many lines of symmetry. Every line can be a line of symmetry for a suitable shape.