What should a Bat Noach do when she sees that her parents are giving all their money to a grandson, with the approval of the rest of the family. while the parents suffer from lack of money? How does the obligation of honoring parents apply here?

Listen, this is a very serious situation that requires you to act with both wisdom and courage. As a Bat Noach, you are absolutely obligated in the mitzvah of honoring parents - this is one of the seven Noahide laws, a fundamental moral obligation that applies to all humanity, not just Jews. The obligation to honor parents means you cannot stand by silently while your parents suffer from lack of money, especially when they are giving away their resources and harming themselves in the process. This is not truly honoring them - it's actually allowing them to be harmed. The rest of the family approving this situation doesn't make it right. Sometimes the whole family can be wrong, and someone needs to have the courage to speak up. Your obligation here is twofold: First, you must respectfully but firmly speak to your parents privately and explain that what they're doing is causing them to suffer. You need to help them see reality. Second, if they won't listen, you should speak to the grandson and explain that accepting money while his grandparents lack basic necessities is wrong and causing them harm. Now, here's something critical you need to understand: honoring parents doesn't mean you have to agree with every foolish decision they make or enable behavior that harms them. When parents are doing something self-destructive, true honor means trying to protect them from themselves, not just nodding your head and watching them suffer. If your parents have money but are giving it all away while they themselves need it for basic living expenses, and you have the ability to help them, you should. But more importantly, you need to stop this foolishness of giving everything to one grandson. This isn't about the grandson's benefit in the long run either - when you give children too much, you're destroying them. You're creating entitled people who think the world owes them everything. The bottom line is this: have a serious conversation with your parents. If they won't listen, speak to the grandson and tell him he needs to refuse this money because his grandparents need it. If the whole family is against you, stand alone. Sometimes doing the right thing means standing by yourself against everyone else. That's what real honor looks like - protecting your parents even when they don't want to be protected.