What kind of a contractor do I need for a bathroom job?

I have to get the grouting or sealant or whatever it is around the bathtub cleared out and replaced. I’d like to hire a pro and not a neighborhood handyman. There’s some black stuff that I want dealt with right.

What kind of contractor should I look for, what should I ask, and any (ballpark) idea of what I should pay?

This is clueless me trying to pick up my late husband’s former duties, which he hadn’t been able to attend to for a while. It was no use pushing him, and I didn’t take over because I didn’t want to make him feel irrelevant. Now I need help, and I’m grateful for any advice.