If she has a pinned front sight blade, you may stand a chance of a DIY replacement being available that already has the vial installed in it.
If not, you'll have to send the entire gun in to have the front sight blade bored and vial installed. The following is one of the firm's that does this type of work... Tooltech Gunsight
That looks really professional. I guess the question is...do I send it to Smith&Wesson first for the refinish or to this guy to have the sights installed. I hope that they don't mess up each other's work.