Your mum needs to submit following documents to Chinese embassy in Tanzania:
1. One completely filled out Visa Application Form for the P.R. China. No item should be blank or altered.
2. One recently taken 2X2 inch photo showing entire face and without a hat on. Please affix the photo to the application form.
3. Original passport with at least 2 blank visa pages and valid for at least 6 months beyond the date of application.
4. Former Chinese visa records (if any, together with their copies).
5. Hotel booking and ticket booking to China.
6. Bank Statement in Tanzania or you can provide yours if you will shoulder all her expenses.
7. Invitation from you, and copies of your passport, work permit and resident permit toghther with the certificate of your relationship.