To answer the subject line: Yes.
Even EE x EE can produce tan or brown eggers. There's no standard for EE so it's pretty much a case of where "anything goes", even if people insist on their being a general look for EEs(such as insisting EE have green legs for example).
As for individual hens, their egg color doesn't change except by as someone mentioned, by the eggs getting lighter as they go thru the cycle and/or some strange things happening as an single egg having a strangely tinted "bloom".
The hen seems to have a pea comb.. I would be slightly skeptical of her being out of a Wyandotte as normally Wyandottes have rose combs, so by that reasoning she should have had a rose comb.. or a walnut comb if it was cross between a Wyandotte and a pea combed EE.
Her tail also look rather long.. so if there's something long tailed over there such as an OEG I'd suspect it's more a cross between an EE and OEG.. or again it could be straight up EE x EE.