Sorry about your father.I give you two suggestions of haircut for your mom.
Suggestion 1– for job, short haircut look is best for your mom.I suggest Bob cut for your mom.
Suggestion 2– give your mom shoulder length haircut, give some layers in front.that give totally corporate lookbto your mom.at office,your mom can put her hair open and make pony also in that haircut.
My mom age is 48 years old. She is also doing job.recently my mom got new haircut.mom got shoulder length haircut.its give to mom corporate look.keep updates.