Is it a condition that the two rak'ahs of Wudu prayer be immediately after performing Wudu, or is it permissible to combine the intention of the two rak'ahs of Wudu with the regular Sunnah prayer of Dhuhr after praying Dhuhr?

It is recommended for a person who has performed ablution (wudu') to pray two rak'ahs immediately after completing the ablution. These are called "Sunnat al-Wudu'" (the Sunnah of ablution). Prophetic traditions have indicated its virtue and that it is a cause for forgiveness and entry into Paradise.

It is permissible to combine the intention for Sunnat al-Wudu' with other prayers, such as obligatory prayers, regular Sunnah prayers, or Tahiyat al-Masjid (greeting the mosque prayer), because Sunnat al-Wudu' is not an independent intention but rather refers to performing prayer after ablution. So, if a Muslim performs a prayer combining several intentions, such as the regular Sunnah of Dhuhr, Sunnat al-Wudu', and Tahiyat al-Masjid, that is sufficient.

However, if these two rak'ahs are delayed for a long time after ablution, their time expires.