Eating after Maghrib and the regular Sunnah prayer of Maghrib

The guidance of the Prophet (peace and blessings of Allaah be upon him) is the most perfect guidance. He used to break his fast with fresh dates; if none were available then with dry dates; if no dates were available then he would drink water. Then he would perform the obligatory prayer in the mosque and the regular Sunnah prayer in his house. 

Anas ibn Maalik said: The Messenger of Allaah (peace and blessings of Allaah be upon him) used to break his fast with fresh dates before he prayed; if there were no fresh dates, then with dried dates; if no dates were available then with a few sips of water. 

Narrated by Abu Dawood, 2365; classed as saheeh by al-Daaraqutni in his Sunan, 2/185; classed as hasan by al-Albaani in Irwa’ al-Ghaleel, 4/45. 

It was narrated from ‘Abd-Allaah ibn ‘Umar that the Messenger of Allaah (peace and blessings of Allaah be upon him) used to pray two rak’ahs before Zuhr and two rak’ahs afterwards, and two rak’ahs after Maghrib in his house, and two rak’ahs after ‘Isha’. He did not pray after Jumu’ah until he had gone home, then he would pray two rak’ahs. 

Narrated by al-Bukhaari, 895; Muslim, 729. 

We do not know of any specific Sunnah concerning the matter asked about in the question. We do not know at all whether the Prophet (peace and blessings of Allaah be upon him) ate anything else after Maghrib prayer. If the Muslim goes home and finds that food is ready and has been served, and he fears that he may be distracted by it when praying, then he should eat first and then pray the two rak’ahs of Sunnah for Maghrib. The time for offering the Sunnah of Maghrib ends when the time for offering the obligatory prayer of Maghrib ends. 

And Allaah knows best.