In Jainism there isn’t a fixed “Pitru diya” ritual like some Hindu practices. So there isn’t a prescribed set of prayers to recite specifically for Pitru (ancestors) during an evening lamp. If you want to observe something at home in a Jain context, you can keep it simple and aligned with Jain practices:

• Light a small lamp or diya in the evening as a symbolic gesture to dispel darkness and cultivate inner clarity.
• Sit for a short moment of reflection or prayer focused on gratitude and nonviolence. A common Jain practice is to chant the Navkar Mantra (Namokar Mantra) to center the mind on the path of right faith, right knowledge, and right conduct.
• Offer daily Dharma activities that honor parents and elders through virtue: speak truthfully, practice kindness, forgive, and share charity. In Jain thought, honoring elders is best expressed through righteous conduct rather than ritual offerings.
• If you wish to read or recite, you can turn to traditional Jain prayers or stotras that emphasize humility, Samayik (meditative reflection), Pratikraman (confession and reflection), and reverence for Tirthankaras.

Bottom line: there isn’t a specific Pitru diya prayer in Jain tradition. You can light a lamp and engage in peaceful reflection or Navkar Mantra, along with daily virtuous conduct to honor your elders in the Jain way.