What is the ruling on a woman seeking help from a strange man to support her when she climbs a wall she jumped from during the ritual of throwing the pebbles (rami al-jamarat), and does this invalidate her Hajj, and what is its expiation?

If the meaning of "he supported me" is that the foreign man placed something for you to step on without direct contact, then there is no harm in that, based on the hadith of Asma bint Abi Bakr, narrated by Muslim, regarding the permissibility of giving a ride to a foreign woman if she becomes tired on the road.

However, if the meaning is that he held you with his hands, then it is not permissible for a woman to allow a foreign man to touch her except in cases of dire necessity, and there is no necessity here. Nevertheless, the Hajj is not invalidated by what occurred.