Mother-in-Law to visit UK after Child delivery

Hello Guys, I need your help!!

I am British citizen with my wife just approximately 9 months here with me with a spousal visa.

1.) What processes/steps do I need to follow to get my mother-in-law/mother to visit us in the UK from Africa after the delivery of our baby?

2.) What documents would I need to submit and financial requirements to meet?

3.) is there any need to be wary about the house/flat, i am presently leaving in a one bed room flat with 2.25 people will it be enough requirement?

I need your help so that I can start planning and gathering all required documents and evidences.

Your fast responses and references will be highly appreciated.