Bismillaah Al-Hamdulillaah wa salatu wa salaamu 'ala rasulullaah
Amma-ba'd
In addition to the above du'aa, which is for the one who provides a fasting people with food to break their fast, here other du'aa - found in Hisnul Muslim - to make for those who feed you and give you to drink, either after fasting or in general.
1- Invocation for a family who invites you to break your fast with them:
Aftara 'Indakumus-Saa`imoona, wa Akala Ta'aamakumul Abraaru, Wa salllat 'Alaykumul-Malaa`ikatoo (With you, those who are fasting have broken their fast, you have fed those who are righteous, and the angels recite their prayers upon you.)
Reference: Abu Dawud 3/367, Ibn Majah 1/556, An-Nasa'i, 'Amalul-Yawm wal-Laylah 296-8. Al-Albani graded it authentic in Sahih Abu Dawud 2/730.
2- A Dinner guest's invocation for his host:
Allaahumma baarik lahum feemaa razaqtahum, waghfir lahum warhamhum (O Allaah, bless them in what You have provided for them, and forgive them and have mercy on them)
Reference: Muslim 3/1615.
3- Invocation for someone who gives you drink or offers it to you:
Allaahumma 'at'im man 'at'amanee wasqi man saqaanee (O Allaah, feed the one who has fed me and drink to the one who has given me drink)
Reference: Muslim 3/126.