My brother b1 visa was denied because i am an asylum applicant in the US, If i dropped my asylum case

I do not believe that you withdrawing your asylum application will make any difference. You will still be in the US, and there will still be evidence of your intent to remain. Instead, your brother should work with an attorney and focus on filing the most persuasive B1 app possible that shows his intent to return to his home country (that is what they're concerned about -- him staying here too). It may still be denied, but family members of asylum seekers do get approved occasionally for visitors visas. Have a private consultation with an immigration so they can consider all the factors here. If it's a matter of safety for your brother and he does not intend and cannot prove that he intends to return home, then again, I suggest you consult with an immigration attorney and see if there's an alternate safety plan that may be possible. Best of luck to you and your family.