Hi! The safest immediate step is to stop all contact, not send any more money, keep screenshots, email headers, payment records, chat history, and the email address they are using as evidence. In Microsoft Teams Free, suspicious chats, messages, images, files, or communities can be reported through Report a concern.. If the contact also came by email, those messages should be reported as phishing/junk as well.
Because money is involved and the victim is elderly, I strongly recommend filing a police report as soon as possible.
If any payment was already sent, contact the bank, card issuer, wire service, or crypto platform immediately to try to stop or reverse the transaction, and ask them to flag the account for fraud.