Hi,
It's a personal view that the once-in-a-lifetime events that produce a life-changing effect see more of a relevance of secondary progressions than solar arc directions. I'm not implying that hypothetical S.A.D's do not work: They are uncannily accurate, yet they do appear to be relevant only during the applying, exact, and separating 3 year period they are in effect, after which the effect 'fades' and wears off. Secondary progressions have a greater and invariably lasting impact.
A secondary progressed chart is seldom read in its own right; its positions are placed against the natal chart
Mother is usually associated with the Moon, perhaps the 4th (as home-maker) or 10th (outer authority) houses, the 5th house of parent-child relationship. In casses of leaving the physical world, Pluto's finality would seem more relevant than Saturn's endings. There can be an association with the 8th house.
With an accurate birth time, it can be seen that secondary progressed Sun has crossed the I.C. to enter the 4th house. This can be associated with a defining effect upon your home life, perhaps sudden as s.p. Sun's position sextiles natal Uranus in the 5th house. Uranus is the modern ruler of Aquarius on the 8th house cusp. S.p. I.C. has crossed 5th house cusp.
S.p. Moon has reached 5*degrees Aquarius where it makes an exact degree square aspect with natal Pluto. The applying T-square it forms in the s.p. chart can be an indication of what your feelings are going through..... which only you can determine.
Transit Saturn in only now conjoining s.p. Moon; Tr. Pluto is crossing natal Desc., thus opposing natal Asc.
'Delayed shock', grief, and what her passing further means may only now be hitting you.
Further transits and S.A.D's (which I have not calculated) will also, over time, have their effect.
My condolences and sympathy upon your loss.