Hello Deumoush.
I only wish I could read your post earlier and reply you sooner.
I would say that it is not easy to find so called "secure house with garden" in malabo as there is no closed compound for °µÍø½ûÇøs as other African countries such as Angola.
However, the security level is relatively good compared to other african nations, therefore, you may be satisfied with conventional house with garden provided that you hire watchmen for day and night
Houses I've have paid visits (mostly with three or four bedrooms, two bathroom, living, kitchen and space to park several cars) were around 1,5 to 2 million CFA monthly basis. However, you might be able to find cheaper houses depending on the neighbourhood.
Water system is poor in Guinea Equatorial except for Mongomo, Evinayong and Ebibeyin. Water in Malabo is from well.
Electricity is connected to most part of Malabo, however, you will often find yourself in the middle of blackout. Therefore, be advised that the emergency electricity generation system (Generator) is needed.
I would be foolish if I give you a recommendation for you salary level since I do not have information on your job, experience, education level, etc. However, it would be wise to aske to your employer to cover all your expenses such as housing, education for your children, food, fuel, communication expenses, and so on..
Moreover, you should multiply at least 1.5 on your regular salary back your home. If your employer is reluctant to cover for your food, you should take into account that most stuff you need for daily life is very expensive as most of them, if not all, are imported from around the Globe.
(I have met people how receive more than twice their salay back there country)
Hope this can give you a general idea.
Best Regards