Both hydrarch and xerarch successions lead to:

Hydrarch succession takes place in ponds or any other water areas. There is progression from hydric conditions to mesic conditions. Xerarch succession takes place in dry areas (such as bare rock surfaces) and there is progression from xeric conditions to mesic conditions. Hence, in both hydrarch and xerarch, mesic conditions i.e. medium water conditions are achieved. So, the correct answer is 'Medium water conditions'.