My mother was diagnosed with broken hip. How will this affect her?

Would seek treatment. Hip fractures generally require treatment as they usually cofine folks to bed and the sequlae of bed rest is not very good. Treating a hip fracture is generally done to keep a person out of bed active and mobile as far as possible.
Surgery likely. Joint used in weight bearing, so broken bones need to be fixed. Healing faster after surgery, lying around for six months or so is very dangerous.