It would be easier to give an answer with horary but I will give it a try.
For the death of a person we have to consider the Maraka Sthana (=death houses) + Maraka Grahas/Marrakesh (Planets that cause death) + Badhaka (Planet of obstruction).
For the Marakas we have to look at the houses 8,7,3,2. 8 is the house of longevity, 7 as 12th of the 8th is the loss of longevity, 3rd is the 8th of the 8th=house of age and the 2nd is the loss of the 3rd. Hence 2nd and 7th houses are the Maraka houses.
Natural Maraka Grahas for taurus ascendant are Moon and Jupiter. Ruler of the 2nd and 7th house are mercury and mars.
Badhaka occures obstacles. Since her asc is in a fixed sign, her badhaka house is the 9th and its ruler is Saturn.
So whenever the Dashas (Mahadasha and Bhuktis) are ruled by Marakas and Badhaka and operates with the houses 6,8,12 it COULD cause death.
If someone dies by drowning we see when L4 is connected to its Navamsa lord and L8 , also Saturn and the 8th house are aspected by malefics:
Sun rules the natal and navamsa 4th house and is located in the 8th house in conjunction with Mercury (Marrakesh) and in sextile aspect with L8 Jupiter. Marrakesh Mars occupies the 11th house in pisces with Rahu. So Rahu is the agent for Jupiter.Ketu+Rahu are squaring Sun+Mercury. Saturn is also in the Rahu/Ketu axis. Badhaka Saturn is placed in the 7th (maraka house). Mars ( as pad-lagna is an indication for an accident) is in square aspect to Moon (associated with water). So she could indeed died by drowning.
To predict her life span we look at the csl 1 and 8-which is for both Saturn. Saturn is badhaka (9th house ruler) as mentioned and located in the 7th house, also owns the 10th and 11th house.Starlord of Saturn is Mercury,owner of the 2nd house. Sublord of Saturn is Moon-occupies the first house and rules the 3rd and 4th. So Saturn strongly signifies the badhaka and maraka houses but is also connected to the houses 1,3,10 and 11. This means that her lifespan will be medium (25-50).
At the time when she disappeared she was under the Dasha of Jupiter/Rahu/Saturn/Sun (Mahadasha/Antaradasha/Pratyantara/Sookshma Dasha= 07.7.-13.7.).
Jupiter is in its own Star and significator of the 10th and 8th house. Sublord of Jupiter is Ketu. Ketu's dispositor is Mercury, which signifies 2nd (maraka house),8th and 9th (on the cusp of the 9th).
Rahu (as agent of Jupiter) and Saturn are both in the Star of Mercury and in the subdimension of Moon. Saturn sits in the 7th and owns the 9th house. So Saturn is badhaka and maraka at the same time. Sun in conjunction with Mercury is secondary maraka and also the Starlord of Mercury. Sun is in its own Nakshatra and in the Sub of Mars. Mars shows the result of the 12th and 7th house. All planets give the result of mercury= 8th,2nd and 9th house. Hence the current Vmd signifies the possibility that she died in this period. Jupiter,Pluto and Saturn are transiting her 8th house and conjoining with natal Sun/mercury.
