A: How can you tell me that your husband left you and the children in good shape financially and then say that your stepson is having trouble getting by? Let's hit rewind and restate your basic issue: Your husband left you in good shape, and you seem to be struggling with how, what, and when to share with the children.
On the one hand, you explain that you're helping out your daughter for what we both can agree is a good cause, but you set her up as a counterpoint to your stepson; you seem to be implying that he's financially irresponsible and always looking for a bailout. If that's the case, then giving him money every time he asks isn't helpful. He's 41 years old, not 21. He and his wife need to learn how to live within their means. Saying no to someone who is disrespectful of money shouldn't give you an ounce of guilt.
But on the other hand, if he's a hardworking, well-intentioned man who's a bit overwhelmed, you should help him. In that scenario, his needs trump your renovation desires.
It seems to me that your confusion stems from the fact that your husband left his estate to you, and along with it, the obligation to allocate it fairly. That means you need to assess the roots of your stepson's financial situation and act accordingly. In life it's important that we do what's right versus what's easy. Not picking up the phone when your stepson calls is easy, but that doesn't mean it's right.