Requiring a cosigner for a lease

[Kristine O.]

Hello there. I am here again to ask your advice and recommendation as a landlord. I have an inquiry from a fourth year college student who has an interest in renting our ADU from June to Sep. He will stay for an internship near our place. I already spoke to his mother who‘S willing to fill up the application and do background check separate from her son. My question is do I have her sign the lease or give her the guarantor form to sign?