Is it permissible for a woman to apply makeup to other women at home, given that these women wear the niqab when going out, and knowing that they will be going to a wedding hall where there will be music?

It is not permissible for a woman to apply makeup for other women if she knows that they intend to adorn themselves with it to attend impermissible events, even if she stipulates that they wear the niqab when they go out. This is because cooperation in sin and transgression is forbidden. However, if the adornment is permissible and for a permissible purpose, and the women do not intend to attend impermissible events, then it is not forbidden to adorn them.