You should be able to apply for a replacement Social Security card from your local SSA office. If you are concerned that your mother would take the new card from the mail, you may want to consider having it mailed to the address of someone who you trust. Good luck.
Apply for a replacement card. http://ssa-custhelp.ssa.gov/app/answers/detail/a_id/251/kw/251/session/L2F2LzEvdGltZS8xMzg2MTkyNTY2L3NpZC82akNLdl9HbA%3D%3D