There’s not a lot of information about this in Scripture. We have the story in Mark 3: 21 where Jesus’ relatives come to seize him, saying, “He is out of his mind,” but it’s not entirely clear from the context of the story what it is that they are concerned about (we also have no idea whether or not Mary was one of these unnamed relatives). Mary is specifically mentioned in the story where some of Jesus’ kin come to find Jesus while he is preaching (see Luke 8:19-21 and Mark 3: 31-35), but we don’t know why they were looking for him or what they wanted to do. Later, in Mark 6:4, while he is teaching in the synagogue of Nazareth, Jesus says, “A prophet is not without honor except in his native place and among his own kin and in his own house.” The verse suggests that perhaps some members of Jesus’ family did not support his ministry. Even if this is the case, though, we can’t say for sure that Mary was one of that number.
There were certainly plenty of reasons why Mary might have worried about her son as he went about his ministry. He was saying and doing things that were making enemies and putting him on the radar of powerful and merciless people. That said, worrying about your child does not mean that you are opposed to his/her actions. Many moms realize that their children have a unique calling and that they will only be satisfied when they are able to live it. And remember that John’s gospel gives us the story of Mary encouraging Jesus to perform his first public miracle at the Wedding of Cana, which marked the beginning of his ministry (John 2:1-11). We don’t know what Mary envisioned that ministry would eventually look like, but the story seems to indicate that she knew her son had a unique role to play, and that she supported him in his beginning steps. It’s worth noting, too, that Mary supported him in his final hours, as we see in the gospel of John when Mary stands at the foot of the cross (John 19:26).