Note, I use whole sign, all planets, and the moon identifies question and the events.
The moon is in the third which is not the best placement to verify the question - it would have been better off in the 4th or maybe 8th but, in the 3rd, it also plays to be the 12th of the Mother (I use the 4th for mother). With that, it appears that the chart should be readable.
The 4th house of your mom ruled by Sun which is at the last degrees of Taurus. The last degree can be termed a chaotic as it may indicate that something happens that is unexpected. This could be negative. It is also moving to an opposition to Saturn but, will not complete until it moves into new sign.
Using the Moon to indicate events and it has quite a few --
- trine Neptune, pisces house is 11th or 8th of mother. Surgery itself looks ok
- conjunct Venus which is 1st house or the 10th for your mom and is the status and this would be positive.
- opposition Pluto which is the 7th house or the 4th for mother and indicates that there is controversy over the end result - would be negative
- square Uranus which is the 10th house or the 7th for your mom and could indicate the surgeon - not positive
- trine Chiron which is the 5th house or the 2nd for your mom which would be what she values - this is positive.
The last aspect is the trine to Chiron which is positive but the steps to get there have some cons.
There might be some disagreement over what the end result will be (moon opp pluto)- I might suggest that you go over all the details with all the people involved again to make sure everyone knows what is expected as the outcome. The Moon Square Uranus might indicate an issue with the surgeon or an issue with the method that is going to be used. It could be that there are different procedures that might be better. It could be that the expected surgeon is not able to do the surgery.
Did your mother get a second opinion? The Moon square Uranus might indicate a second opinion that differs from the initial. Note, this does not say that the 1st opinion is wrong just some differences in opinion.
It could also be that your mom might need surgery earlier and that could result in some changes in the plan that could explain the events.
There could be another series of events but, running out of time to detail them out. Maybe tomorrow more time.