How do I file a fraud request on someone? She filed taxes on my kids when she was only able to claim one. And she attempted to file on my recently deceased husband.?

Use IRS Form 3949-A, Information Referral.

It can be completed either online or mailed to the IRS - https://www.irs.gov/forms-pubs/about-form-3949-a

since your husband passed in 11/22, you can file a joint 2022 return. you can claim all the dependents you are entitled to. See below. Form 1310 (refund due a deceased taxpayer) may be required. See There is no way you can e-file for 2022 so there is no reason to wait to file.  Follow the Turbotax filing instructions when mailing your return.  I would use a service where you track your return. The IRS will eventually send you and the other woman a letter asking to amend your return. If it is you who properly claimed the dependents then do nothing. if the other woman doesn't amend the IRS will send a second letter to each of you asking for proof that you're the one entitled to claim the kids. the letter will contain examples of what constitutes proof to the IRS. The loser likely will get a big tax bill along with penalties and interest. 

these are the rules for claiming a qualifying child as a dependent.

Qualifying child – and eligible to be claimed as a dependent the rules are:
1) Related - son. daughter. stepchild, eligible foster child, or a descendent of any of them; brother, sister, half-brother, half-sister, stepbrother, stepsister or a descendent of any of them. Adopted child if legally adopted or an individual lawfully placed with the taxpayer for legal adoption. Eligible foster child is one placed with the taxpayer by an authorized placement agency or by judgment decree or order of any court with jurisdiction
2) Same principal abode as the taxpayer for more than ½ the tax year. Temporary absences like
for school are ignored. 
3) If not a full-time student, under 19 at the end of the tax year. If a full-time student under 24 at end of tax year.
Full-time means an individual who during each of 5 calendar months during the calendar year in which the taxable year of the taxpayer begins is a full-time student at an educational organization described in section 170(b)(1)(A)(ii), or is pursuing a full-time course of institutional on-farm training under the supervision of an accredited agent of an educational organization described in or of a State or political subdivision of a State.
4) Hasn’t provided over ½ his/her own support
5) Hasn’t filed a joint return – unless there is no tax liability
6) A US citizen, resident alien or national, or a resident of Canada or Mexico
7) If a qualifying child of more than one person there are tie-breaker rules

if neither of you meet all the tests to claim any of the children as a qualifying child then maybe the child can be claimed as a qualifying relative - 

Qualifying Relative and eligible to be claimed as a dependent the rules are:
1) Live in your household the entire year. Absences for medical treatment are ignored
2) gross income for 2022 less than $4,400
3) you provide over ½ his support
4) isn’t a qualifying child of another taxpayer

don't understand about the children's income. in certain cases a parent can include a child's unearned income on their return. this is not possible for a non-parent. in most cases if the child's income is high enough, they have to file their own return. 

check the 1040 instructions charts B and C to see if they have to file their own returns.

https://www.irs.gov/pub/irs-pdf/i1040gi.pdf