What is the ruling on a girl's father attending his daughter's wedding ceremony, which will be held in a hall with music and mixing, based on the wishes of the groom's family and his weak religious commitment? And does this matter prevent it, with the possibility of greater problems arising and the husband abandoning his daughter?

There is no obedience to anyone in disobedience to Allah. Whoever pleases Allah by displeasing people, Allah will be pleased with him and will make people pleased with him. And whoever displeases Allah by pleasing people, Allah will be displeased with him and will make people displeased with him. You must forbid your daughter's husband from the evil with gentleness and kindness, and explain to him the impermissibility of what he is doing, and that he should not begin his married life with disobedience to Allah. If he does not respond, then do not attend the forbidden celebration and explain to him and your daughter that you will not attend out of fear of Allah.