She may not need to refile for her children if she became a US citizen before they married - it is unclear which category she originally filed for her children if at all. Ideally you would want to salvage the original I-130s because the backlog is so long to obtain a visa for many countries in the family-based categories. Refiling today means waiting several more years. Unfortunately, family illness does not hasten the process. It is possible her children may come over on a different type of visa but you need to provide an attorney more details on their skills/education and nationality.