यन्मातापितरौ वृत्तं तनये कुरुतः सदा । न सुप्रतिकरं तत्तु मात्रा पित्रा च यत्कृतम् ॥

श्रीमद्वाल्मीकिरामायणे अयोध्याकाण्डे एकादशोत्तरशततमस्सर्गः (९ श्लोक)

“However great a person maybe, it is impossible for him to return the favours done by his parents” said ShriRaama while replying to sage Vasishtha.

Hence the only thing progeny can do is to keep serving their parents without any interruption and without any deficit.