demismama; The rear brake condition and adjustment will directly affect the brake pedal height. If the rear brakes need to be replaced, or at least adjusted, you need to do that, first. (I'm assuming that they are drum brakes in the rear). The front disc brakes are not 'adjustable'. The pistons must be depressed, back into the calipers, to accept the new pads. When doing so, the brake bleeder on the caliper should be opened so as not to 'push' old, dirty, fluid backwards thru the ABS system and into the master cylinder. If the master cylinder was allowed to go empty during the brake replacement, chances are that you will need to bleed the whole system, front and rear. Starting with a master cylinder full of new brake fluid, open the RR bleeder. While keeping the master cylinder full, allow the fluid to flow thru the bleeder until it is nice and clean, no air bubbles. Then, move to the LR and do the same. Then, the RF. Then, the LF. If this does not solve your problem, it would seem that the master cylinder primary cup has been damaged. When bleeding brakes, if someone pushes the brake pedal to the floor while bleeding, this can happen quite easily. Assuming the rear brakes are adjusted and all of the air is out of the system: If you can pump the pedal a couple of times and have a good pedal, Bad master cylinder. If you have a good pedal, with your foot on the brake, put in gear, and the pedal starts creeping towards the floor, Bad master cylinder (assuming no hydraulic leaks).
Now, with all that said, let me know if the rear brakes are disc. If so, then we need to do a little more. (try applying the parking brake while pumping the brake pedal to see if that helps)