Anybody from the approved countries can come to qatar on on-arrival visa.(Visa Waiver).

It can be wife, mother, daughter, uncle, uncles son, neighbour son, neighbour sons daughter.... :)

Just keep following documents ready to avoid immigration issues at airport:

1) Passport with validity more than 6 Months

2) Return Ticket

3) (Not required officially...but keep this one ....if you think too much) Address proof of the accommodation in qatar...A person with Qatar ID can write a letter stating he has arranged accomodation in his house and he takes residential and financial responsibility.

4) (Not required officially.....but keep this one ....if you think too much)... A statement of your bank account.