Extension visit visa

That really depends on the discretion of immigration.  A 1 month visa can be extended up to 3 times and then after that, the chances drop.  I have seen a 4th or 5th extension rarely.  And that depends on the PRO and his relationship.

If the extension doesn't happen, she has to exit and re-enter on a new visa.

Thanks for the response. I want to buy here a housemaid visa but they said she is over age my mom is 58 years old. They offering working visa but it's too expensive. It's true until 57 only the housemaid visa?

It is difficult to get housemaid visa at more advanced ages and for nationalities which are the same as the sponsor.  This is to prevent exactly the kind of abuse you are aiming to do.

Also, the work visa that you are referring to is NOT legal.  Someone who has a company and has spare visas is offering one to you for 1000-2000 BD as a so-called "Free visa".  It is absolutely illegal and it is not allowed to do that.   You can do that and if nothing happens, it is all ok.  But if tomorrow there is an inspection of that company and they find something, your mother will be in trouble.   Besides, the retirement age in Bahrain is 60 years and in a couple of years, you will face difficulty in renewing her visa.

The only long stay option is to sponsor parents for residence visa.  Unfortunately, that process is not easy, requires a LOT of contacts or you to be working for a very big company and you must have a high profession / income.  I had all of that and was sponsoring my mother but it took over 4 months to get an approval.  The other option is to set up a company and get her an investor visa which doesn't have age requirements.  But expect to pay a couple of thousand BDs each year to keep the company running.

Thanks for the information. I heard also that it's possible to get sponsor for parents if the cases that that they alone and no one will take care of them.

No.  This is part of what I said above.  It is easier if they are alone (vs. both still alive) and you show that you are supporting them but you still MUST have either the contacts or work for a big company, have a managerial profession plus income.   And as I said, that was EXACTLY my case as my mother was alone - but it took time for the approval despite me being at a director level (Company representative with all government bodies and Embassies), working for a very big multinational, having company & personal contacts and in a very high salary range (in the upper 1%).   Before me, the CEO who was a westerner was refused for his mother - so it is a collection of variables, not just one.