My mom is on drugs and knows I won't let her see my son so she's constantly calling him and he just hits ignore but it's causing problems with our marriage because she's calling him to get to me and he can't change his number die to corporate job
OK. So in one place you say your husband's phone and in the other you say your son's phone. Obviously it can't be both.
So unless the phones are on the same account as yours, and you have access to the online account for them, you have no way to block another persons phone. Not at least without doing something you shouldn't do and that we can't help you do.
Now, you can just have them put a block on that number on their device (who ever it actually is). They can do that through their contacts. It is extremely simple.