Is it permissible for a woman to attend a wedding party where there is music, dancing, and immodest dress? And is her guardian sinful if he permits her to do so? And what is the ruling if the invitation is from a relative whose not accepting the invitation is feared to result in abandonment and severance of kinship ties?

It is not permissible to accept invitations to weddings that involve forbidden acts, unless one is able to remove the forbidden act. If one is unable, then it is not permissible for him to attend, nor is it permissible for him to allow his wife or daughter to attend. If abstaining from attendance results in coldness or estrangement, then the sin falls upon those who disobeyed Allah in these celebrations.