Hi,
5Hz Resolution at 2MHz is is 1 in 400,000 or 0,00025%! This implies that you are either trying to measure very accurate capacitors or your circuit has a very small frequency change for a given capacitance change.
Without knowing exactly what you are trying to acheive (parameters to be measured, range of values and accuracy) and the circuit you are using, it is hard to make reasonable suggestions. Is this just a project to make a LC meter for your own use, a special meter for a particular application or a commercial design?
If you wish to use an external hardware counter look at the CMOS (CD/HEF) 4040 (12 bit, use two) or 4518 (dual 4 bit, use 3 ic's) chips but you will have to build your own gating and multiplexing circuits, or the Intersil 7226. The 7226 is an 8 digit frequency counter ic that will drive LED's but also has a multiplexed BCD output. It is however becoming obsolete.
I do think howevr that if you need 5Hz resolution at 2MHz to measure at normal component accuracy (around 1%) your circuit needs to be reconsidered. Perhaps auto range switching when the PIC counter overflows? My code traps a counter overflow.

A typical precision LCR meter costing around $4000 offers 0.05% accuracy, 0.2% will cost you $2000 and 1% about $200.
I can recommend the Peak Atlas LCR meter at under £80 (UK Pounds) or about $150.

HTH,
Robert.