All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
It is not legislated to bow down when greeting someone even if he is an old person, and it is forbidden to do so if bowing is in the same manner as Ruku’ (bowing in the prayer). If a person does this as a way of glorifying the person (to whom he bows down) in the same way he glorifies the Creator (Allaah), then this is an act of disbelief. Therefore, you are obliged to avoid doing this in any case, and the best guidance is that of the Prophet .
For more benefit, please refer to Fataawa 84465 and 88171.
On the other hand, raising the hand, while greeting a person with Salaam, is permissible. It is reported that the Prophet passed by a group of women who were sitting in the mosque and he raised his hand [towards them while] greeting them with Salaam. [Ahmad and At-Tirmithi]. This means that he combined between greeting with Salaam and raising the hand, as stated by the scholars.
Allaah Knows best.