Hi and welcome
I am ever so sorry for your loss!
We have got comprehensive practical and helpful information on what you can do for a bereaved companion in the short term and help with human grieving (including resources for children) and information about the dying process/euthanasia in case you feel somewhat traumatised and have the need to make sense of what has just happened or you suffer badly from feelings of guilt or failure via this access link here:
Death, Dying, Terminal Illness, Grieving and Bereaved Companions: Information and Support for Owners and Their Children
While you can place a single boar next to two sows, you can't unfortunately do the opposite with a sow next to bonded boars without risking fights and fall-outs as the boars react strongly to sow pheromones they are not used to.
You can find the rules re. boars and sows in our chapter about dos and don'ts in our boar guide:
A Comprehensive Guide to Guinea Pig Boars
Please give your girl time to do her own grieving. As long as she is eating and drinking, you have ideally 1-4 weeks to look for a new companion for her.
Can you get to this rescue in Baton Rouge? It is the only recommended good welfare standard guinea pig rescue listed for your state.
Guinea Lynx :: US Guinea Pig Rescue and Shelter Organizations
Otherwise please follow the advice for for finding new company for single guinea pigs in our singles guide, which also looks at bereaved guinea pigs and the specific challenges involved. If you have to buy or privately rehome a piggy, please be aware that you need to make provision in case of a character match not happening during bonding and that you may keep the new companion (either another sow or a neutered boar) in and adjoining cage for mutual interaction and stimulation through the bars.
Character compatibility and acceptance is unfortunately not something you can ever predict.
Single Guinea Pigs - Challenges and Responsibilities
New guinea pigs: Sexing, vet checks&customer rights, URI, ringworm and parasites
PS: I am moving this guide to our Behaviour, Bonding and Bereavement section for you.