Queen Mallika story and stream entry I was wondering about the story of queen Mallika, she seems like someone who entered the stream, nevetheless she went to hell after passing away.

Is it possible for someone to be reborn on the awful planes after entering the stream? I thought it was impossible
In AN 3.86 it is taught that a stream enterer will be born in human and deva realms for a maximum of seven life times:

&quot;[Some,] with the wasting away of the three fetters, are
'one-seed-ers' (ekabijin): After taking rebirth only one more time on
the human plane, they will put an end to stress.
&quot;Or, not breaking through to that, not penetrating that, with the
wasting away of the three fetters they are 'family-to-family-ers'
(kolankola): After transmigrating &amp; wandering on through two or three
more families [according to the Commentary, this phrase should be
interpreted as 'through two to six more states of becoming'], they
will put an end to stress.
&quot;Or, not breaking through to that, not penetrating that, with the
wasting away of the three fetters they are 'seven-times-at-most-ers'
(sattakkhattuparama): After transmigrating &amp; wandering on among devas
&amp; human beings, they will put an end to stress.&quot;
AN 3.86 

In Great Disciples of the Buddha: Their Lives, Their Works, Their Legacy, by Nyaponika Thera it is mentioned that she wasn't a stream enterer at the time of her death. He gives the reason for her birth in hell as:

When Mallika died her twofold transgression-her sexual contact with the dog and her mendacious attempt to free herself from blame-caught up with her and brought about a rebirth in hell.

and later he says,

Although it was a very short-termed sojourn there, one can see that Mallika had not yet attained stream-entry during her life on earth...