All perfect praise be to Allah The Lord of the Worlds and may His peace and blessings be upon our Prophet Mohammad and upon all his family and companions.
Serving the slaves of Allah, especially those who pray in mosques during Ramadan and else, is amongst the good deeds encouraged by Islam. This noble act is an actual fulfillment of helping one another in righteousness and piety, which is a sufficient reason for incurring the love of Almighty Allah.
The Messenger of Allah (PBUH) said: "The most beloved to Allah are the most beneficial to the people." {Related by Tabarani}. Prophet Mohammad (PBUH) has made clear that whoever serves the fasting or the praying people will have a reward similar to theirs, and even more. Anas (Allah be pleased with him) reported: "We were with the Messenger of Allah (PBUH) on a journey. Some of us had been observing the fast and some of us had not been fasting. We got down at a place on a hot day. Most of us had the cloth for shelter. There were also those amongst us who sheltered (themselves against the rays of the) sun with the help of their hands. The observers of the fast fell down (because of weakness). Those who had not observed it got up, pitched tents, and watered the mounts. Thereupon the Messenger of Allah (PBUH) said: "The breakers of the fast have taken away the reward today." {Related by Muslim}.
In his commentary on "The breakers of the fast have taken away the reward today," Al-Khastalani {May Allah have mercy on him } said: "It is the reward they received for pitching the tents, watering the mounts and similar good deeds that were beneficial to others. They have also received the same reward as that of those who were observing fast. As for the latter, they have just received the reward of fasting." {Irshaad As-Sari, V.5/P.88}.
In conclusion, we pray that Allah grants the above persons a reward similar to that of those offering Isha` and Taraweeh prayers; knowing that they are keen on observing those prayers after the congregation is finished. And Allah knows best.