After seeing Jesus's body laid in the tomb, Mary might have chosen to visit it again “with spices” (to mix with water) in order “to anoint” Jesus's body.
But wait, that seems unlikely for two reasons:
Mary would anticipate that the stench of Jesus's rotting corpse would be overwhelming by Easter morning.1
But wait …
Mary would notice beforehand that she could not move the massive blocking-stone at Jesus's tomb by herself.[See evidence and response]1 This would obviously be relevant because, in conjunction with other reasons, Mary's knowing Jesus's tomb was sealed would be sufficient to deter her from visiting it.
◦ Christopher Bryan (NT professor at Sewanee): “…if there were any reminiscence behind Mark's story [16:2-4], we would surely need to admit that Mary of Magdala and her companions will hardly have been the first or last people in the history of the world to have been moved by strong emotion to attempt something without knowing how they were going to do it, or even without noticing until the last minute an obvious difficulty.” [The Resurrection of the Messiah (Oxford, 2011), 76.] So if the prior probability is higher that Mary would notice before setting off, it need not be that much higher (i.e. the argument here is not particularly strong, contra Brown, The Death of the Messiah, 1311.).
Mary would know that soldiers were guarding Jesus's tomb.1
But, so what? Couldn't it simply be that…
• Matti Kankaanniemi: “Friday and Sunday, while - in all likelihood – they spent the Sabbath, the Saturday, ‘the day of the guards’, at someone’s home. In the Markan storyline when the women arrive at the tomb the angel is already seated on the rolled stone. It is therefore possible, in principle, that the women never saw a single guard at the tomb, even if guards had been posted there.” [The Guards of the Tomb (Åbo Akademi, 2007), 29.]