Bio-diesel is mostly produced by plants from the family Euphorbiaceae. Euphorbiaceae is a family of flowering plants that includes several species known for their ability to produce oil-rich seeds. These seeds are processed to extract oil, which can then be converted into bio-diesel through a process called transesterification.

Option 1: Myrtaceae is a family of flowering plants that includes species like eucalyptus and clove. While some species within this family may produce oil, they are not widely used for bio-diesel production.

Option 2: Malvaceae is also a family of flowering plants that includes species like cotton and hibiscus. Similarly, although some species within this family may produce oil, they are not commonly used for bio-diesel production.

Option 3: Liliaceae is a family of flowering plants that includes species like lilies and tulips. However, plants from this family are not known for their oil production and are not used for bio-diesel production.

Therefore, option 4 - Euphorbiaceae is the correct answer.