Christiane, AirBnB does not condone third-party bookings.
https://www.airbnb.com/help/article/427/can-i-book-on-behalf-of-a-friend-or-family-member
There are several reasons for this, one being that the person who made the reservation is held to be responsible for any guest-related damages that might occur during the visit.
Perhaps - as suggested in the link - you could ask the daughter to help her mother register with AirBnB so that she can make her own reservation.
I hope other - more experienced - hosts will respond to your question, and with specific details about third-party-booking risks.