Thanks @Fabla for your always insightful examples! I believe @debu_odk needs to capture all household members and then only consider the women between 18-25 when choosing a random respondent. Your example only allows for up to 4 women's information to be captured.
@debu_odk it sounds like you've been able to get the form working as you wanted with the information above. Could you please post what you have come up with so others can learn from it? This will particularly help @billowabdi who was looking for a similar example in Randomly Selecting a Respondent from Household Members.