All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
Needless to say, music, free mixing between men and women, and dancing are all forbidden. It is incumbent on Muslims to fear Allaah and avoid such forbidden things, especially if they are known for their righteousness and works of charity.
As for the ruling on helping this organization, it requires some elaboration:
It is impermissible to help them commit such prohibited acts; Allaah, The Exalted, says (what means): {And cooperate in righteousness and piety, but do not cooperate in sin and aggression. And fear Allaah; indeed, Allaah is severe in penalty.}[Quran 5:2]
Whoever participates in or helps the organization commit such prohibited acts is sinful for that and is obliged to repent from it.
There is no harm in helping them with charitable and lawful activities that are free from all prohibited acts and contraventions of the religion. If people donate their money to this organization in order to participate in its charitable activities, then it is impermissible for the people administering it to spend this money in anything other than those charitable activities.
If the donors do not know how the organization is spending their money and suspect that they may spend it on prohibited activities, then they should not donate to it and they should give their money in charity by themselves or seek another reliable organization or find a trustworthy person to spend this money in charity on their behalf.