Microbes in Human Welfare

Biological control is the use of living organisms to control pests and pathogens.
Paecilomyces lilacinus is a soil fungus that parasitises the eggs, egg masses and females of plant-parasitic nematodes such as the root-knot nematode (Meloidogyne).
Its hyphae penetrate the nematode eggs and destroy them, so it has proved effective for the biological control of nematodal diseases in plants.
Gliocladium virens is used as a biocontrol agent against soil-borne fungal pathogens.
Pisolithus tinctorius is an ectomycorrhizal fungus that helps trees in the absorption of nutrients.
Pseudomonas cepacia is a bacterium used against some soil-borne fungal diseases.
So the organism effective against nematodal disease is Paecilomyces lilacinus.

$Rhizobium$ is a symbiotic nitrogen fixer of the root nodules of legumes, and $Frankia$ forms nodules on the roots of non-leguminous plants such as $Alnus$; neither is associated with paddy.
$Azospirillum$ is a nitrogen-fixing bacterium that lives in loose association with the roots of grasses and cereals, including rice; it is the answer accepted in the key.
$Oscillatoria$ is a cyanobacterium; cyanobacteria ($Anabaena$, $Nostoc$, $Oscillatoria$) are also important nitrogen fixers of paddy fields.
The answer accepted in the key is $Azospirillum$.
Note: NCERT states that in paddy fields cyanobacteria serve as an important biofertiliser, so $Oscillatoria$ is given as the answer in some books; the key of the source PDF is retained here.

Green manuring is the growing of a quick-growing crop (usually a legume) and ploughing it into the soil while it is still green. It adds organic matter and, through root nodules, fixed nitrogen to the soil.
Crotalaria juncea (sunn hemp) is a leguminous plant widely used as a green manure crop.
Alhagi camelorum (camel thorn) is a deep-rooted leguminous desert plant that grows in sandy soils and is used to improve sandy soils.
Calotropis, Phyllanthus, Saccharum munja, Lantana and Dichanthium are not leguminous green manures (Lantana is a weed; Azolla, a fern, is a biofertiliser used in rice fields, but it is paired here with a grass).
So Crotalaria juncea and Alhagi camelorum are used as green manure.